Need photos.
My Guess??
You aint fed em in 3 weeks??? I feed mine as soon as the first true leaves appear. 10%-15% recommended dose.
Id say starving.
Start feeding it. And don't over water it. If it takes more than 3-4 days before it needs water again, its been overwatered.
I use a cheap Lowes Moisture Meter, and NEVER let the needle get to LOW MOIST LINE. Always just slightly Above the line.
If you let a plant get dry, and then water it, this can cause nutrient burn, as the salts are concentrated if it gets to dry, and when you add water, it (Can ) burns them. If the salts are kept in suspension, this wont happen. It adds to the misery if you also feed it at this time.
Don't overdo it by trying to play catch up either.
My general rule is give them 10%%-25% recommended dose, and feed at each watering. If it says 1tsp per gallon water, I use 1tsp per 5 gallons. Bigger they get, they get slightly more food, and water.
Don't forget Cal/Mag, or Epsom Salts.
You also need to know PH.