curling of leaves

The most common causes of indoor leaves curling upward are too little water, low humidity, insufficient light, or high temperatures. Verify the plant's soil is not dry and PH water. Good Lucky

Burning from feeding too much, too often or both.

bad watering habits exacerbating a potential nute imbalance... would be better to see how it progressed. oculd be high p or too much N or a couple things coinciding. fix watering habits first and don't do anything too dramatic with fertilizer in the meantime unless it heads dowhill too fast to be patient. 1) fully saturate, never half-ass water no matter what you perceptions of "overwatering" are. 2) wait for top 1" to dry and repeat. Keep it simple. When you know more you can push that a bit more, but keep a good wet-dry cycle until then. You always want some minimum loss of weight/dryback before re-irrigating. you always want to fully saturate the medium and some minimal runoff ensures that. how often you add fertilizer depends on how concentrated it is that you add. every other? every third? personal preference but in general you'll get better growth th emore frequent/consistent it is. this is part of why soilless/hydro grows faster. if soiless, it's virtually the same idea... except you want a minimum 10% runoff every time and you shoudl fertiilze every time.

looks like too much water or too much nutrients

When I seen this in my grows it was normally caused by the medium going off. either over watering/bad watering habbits or an overgrowth of bad microbs/bacteria. hopefully someone else has more insight. Might be best to start a diary.

Are pots drying out between watering? What is the ph of the water/feedings? What are you feeding them? How much are you feeding them? What soil are you using? How long is your soil taking to dryback? Without more info there isn't much to say. Without any info my guess is likely over feeding nitrogen, and probably nutrient lockout. Why you ask? Leaves on plant look dark healthy green, which means there was ample food until there wasn't. (Lockout) Newer growth does seem to have a bit of tip burn and clawing maybe, hard to tell from pictures? If your watering habits are alright (soil drying out between watering and feedings, and assuming you are using salt nutrients not organic watering and feeding to runoff) then I would put my money on over feeding veg nutes. If you are running organic then most likely its being overwatered. But that is a guess based on absolutely no information other than a few pictures.

With zero information on your grow it’s hard to say what’s going on. The one thing I see is a small pot. They look like they need to be transplanted into a bigger pot. That would be my first course of action and see how they bounce back. I’d be looking at a three or a five gallon pot at this point. Good luck.