Does anyone know what causing this?

So I'm a new grower had some advice the other day thought I may have overwatered I am leaving the plant to dry out but it seems too be getting worse looking for any advice that can help me fix this problem.
Thanks in advanced.

Yeah looks like overwatering if you have a way to raise the hummidity in the room in the room a bit and back off on the watering it’ll bounce back eventually.
Rule of thumb I like to go by is never water two days in row when they are at that stage. I usually use a spray bottle until I move them into 2 gallons.

Okay thanks for the advice much appreciated