| STOCK OPTIONS AND WARRANTS (Tables)
 | 3 Months Ended | 
| Jul. 31, 2021 | 
|---|
| Share-based Payment Arrangement [Abstract] |  | 
| Assumptions | 
  
    | Assumptions |  |  |  |  |  |  |  
    |  |  | Three Months Ended July 31, |  |  
    |  |  | 2021 |  |  | 2020 |  |  
    | Risk-free interest rate |  |  | 0.87% |  |  |  | 0.3% |  |  
    | Expected volatility |  |  | 113% |  |  |  | 91% |  |  
    | Expected lives (years) |  |  | 2.5 |  |  |  | 2.5 |  |  
    | Expected dividend yield |  |  | 0.00% |  |  |  | 0.00% |  |  | 
| Stock option activity | 
  
    | Stock option activity |  |  |  |  |  |  |  |  |  |  
    |  |  | Options |  |  | Weighted Average
 Exercise Price
 |  |  | Weighted Average
 Grant Date
 Fair Value
 per Share
 |  |  
    |  |  |  |  |  |  |  |  |  |  |  
    | Outstanding, April 30, 2021 |  |  | 41,333 |  |  | $ | 79.97 |  |  | $ | 79.97 |  |  
    | Issued |  |  | 1,000 |  |  |  | 23.10 |  |  |  | 23.10 |  |  
    | Forfeited |  |  | – |  |  |  | – |  |  |  | – |  |  
    | Exercised |  |  | – |  |  |  | – |  |  |  | – |  |  
    | Outstanding, July 31, 2021 |  |  | 42,333 |  |  | $ | 78.63 |  |  | $ | 78.63 |  |  
    | Exercisable, July 31, 2021 |  |  | 39,833 |  |  | $ | 82.93 |  |  | $ | – |  |  
    | Vested and expected to vest |  |  | 42,333 |  |  | $ | 78.63 |  |  | $ | – |  |  | 
| Unvested stock option activity | 
  
    | Unvested stock option activity |  |  |  |  |  |  |  
    |  |  | Options |  |  | Weighted Average
 Grant Date
 Fair Value
 per Share
 |  |  
    |  |  |  |  |  |  |  |  
    | Unvested, April 30, 2021 |  |  | 4,000 |  |  | $ | 10.05 |  |  
    | Granted |  |  | 1,000 |  |  |  | 23.10 |  |  
    | Vested |  |  | (2,500 | ) |  |  | – |  |  
    | Forfeited |  |  | – |  |  |  | – |  |  
    | Unvested, July 31, 2021 |  |  | 2,500 |  |  | $ | 10.05 |  |  | 
| Schedule of options by exercise price | 
  
    | Schedule of options by exercise price |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  
    | Exercise Price |  |  | Number of Options
 Outstanding
 |  |  | Weighted Average
 Remaining
 Contractual Life
 (Years) of
 Outstanding
 Options
 |  |  | Weighted Average
 Exercisable
 Price Per Share
 |  |  | Number of Options
 Exercisable
 |  |  | Weighted Average Exercise Price
 of Exercisable
 Options
 |  |  
    | $ | 156.00 |  |  |  | 6,967 |  |  |  | 0.39 |  |  | $ | 156.00 |  |  |  | 6,967 |  |  | $ | 156.00 |  |  
    | $ | 87.00 |  |  |  | 1,634 |  |  |  | 0.69 |  |  | $ | 87.00 |  |  |  | 1,634 |  |  | $ | 87.00 |  |  
    | $ | 110.10 |  |  |  | 800 |  |  |  | 0.75 |  |  | $ | 110.10 |  |  |  | 800 |  |  | $ | 110.10 |  |  
    | $ | 109.35 |  |  |  | 1,200 |  |  |  | 0.94 |  |  | $ | 109.35 |  |  |  | 1,200 |  |  | $ | 109.35 |  |  
    | $ | 133.50 |  |  |  | 800 |  |  |  | 0.96 |  |  | $ | 133.50 |  |  |  | 800 |  |  | $ | 133.50 |  |  
    | $ | 82.95 |  |  |  | 333 |  |  |  | 0.60 |  |  | $ | 82.95 |  |  |  | 333 |  |  | $ | 82.95 |  |  
    | $ | 83.70 |  |  |  | 6,000 |  |  |  | 0.85 |  |  | $ | 83.70 |  |  |  | 6,000 |  |  | $ | 83.70 |  |  
    | $ | 80.10 |  |  |  | 800 |  |  |  | 2.10 |  |  | $ | 80.10 |  |  |  | 800 |  |  | $ | 80.10 |  |  
    | $ | 80.85 |  |  |  | 667 |  |  |  | 0.88 |  |  | $ | 80.85 |  |  |  | 667 |  |  | $ | 80.85 |  |  
    | $ | 102.45 |  |  |  | 333 |  |  |  | 0.96 |  |  | $ | 102.45 |  |  |  | 333 |  |  | $ | 102.45 |  |  
    | $ | 97.35 |  |  |  | 333 |  |  |  | 1.10 |  |  | $ | 97.35 |  |  |  | 333 |  |  | $ | 97.35 |  |  
    | $ | 74.25 |  |  |  | 6,000 |  |  |  | 1.58 |  |  | $ | 74.25 |  |  |  | 6,000 |  |  | $ | 74.25 |  |  
    | $ | 57.00 |  |  |  | 800 |  |  |  | 3.15 |  |  | $ | 57.00 |  |  |  | 800 |  |  | $ | 57.00 |  |  
    | $ | 60.60 |  |  |  | 667 |  |  |  | 1.38 |  |  | $ | 60.60 |  |  |  | 667 |  |  | $ | 60.60 |  |  
    | $ | 55.50 |  |  |  | 333 |  |  |  | 1.46 |  |  | $ | 55.50 |  |  |  | 333 |  |  | $ | 55.50 |  |  
    | $ | 51.00 |  |  |  | 333 |  |  |  | 1.6 |  |  | $ | 51.00 |  |  |  | 333 |  |  | $ | 51.00 |  |  
    | $ | 61.20 |  |  |  | 6,000 |  |  |  | 2.06 |  |  | $ | 61.20 |  |  |  | 6,000 |  |  | $ | 61.20 |  |  
    | $ | 36.00 |  |  |  | 667 |  |  |  | 1.88 |  |  | $ | 36.00 |  |  |  | 667 |  |  | $ | 36.00 |  |  
    | $ | 37.05 |  |  |  | 333 |  |  |  | 1.96 |  |  | $ | 37.05 |  |  |  | 333 |  |  | $ | 37.05 |  |  
    | $ | 15.75 |  |  |  | 333 |  |  |  | 2.10 |  |  | $ | 15.70 |  |  |  | 333 |  |  | $ | 15.70 |  |  
    | $ | 10.05 |  |  |  | 6,000 |  |  |  | 2.65 |  |  | $ | 10.05 |  |  |  | 3,500 |  |  | $ | 10.05 |  |  
    | $ | 26.55 |  |  |  | 667 |  |  |  | 2.38 |  |  | $ | 26.55 |  |  |  | 667 |  |  | $ | 26.55 |  |  
    | $ | 16.20 |  |  |  | 333 |  |  |  | 2.46 |  |  | $ | 16.20 |  |  |  | 333 |  |  | $ | 16.20 |  |  
    |  | Total |  |  |  | 42,333 |  |  |  | 1.44 |  |  | $ | 78.63 |  |  |  | 39,833 |  |  | $ | 82.93 |  |  | 
| Warrant activity | 
  
    | Warrant activity |  |  |  |  |  |  |  
    |  |  | Warrants |  |  | WeightedAverage
 Exercise Price
 Per Share |  |  
    | Outstanding, April 30, 2021 |  |  | 2,981 |  |  | $ | 58.70 |  |  
    | Issued |  |  | – |  |  |  | – |  |  
    | Exercised |  |  | – |  |  |  | – |  |  
    | Expired |  |  | – |  |  |  | – |  |  
    | Outstanding, July 31, 2021 |  |  | 2,981 |  |  |  | – |  |  
    | Exercisable, July 31, 2021 |  |  | 2,981 |  |  | $ | 58.70 |  |  | 
| Schedule of warrants outstanding and exercisable | 
  
    | Schedule of warrants outstanding and exercisable |  |  |  |  |  |  |  |  |  |  
    | Exercise Prices |  | Number of Warrant Shares
 Exercisable at
 July 31, 2021
 |  |  | Weighted Average
 Remaining
 Contractual
 Life Years
 |  |  | Weighted Average
 Exercise Price
 Per Share
 |  |  
    |  |  |  |  |  |  |  |  |  |  |  
    | $97.50 |  |  | 513 |  |  |  | 0.39 |  |  |  |  |  |  
    | $86.25 |  |  | 580 |  |  |  | 0.68 |  |  |  |  |  |  
    | $37.50 |  |  | 1,333 |  |  |  | 0.99 |  |  |  |  |  |  
    | $45.00 |  |  | 555 |  |  |  | 0.81 |  |  |  |  |  |  
    |  |  |  | 2,981 |  |  |  | 0.79 |  |  | $ | 58.70 |  |  |