Suddenly he is not well. Or is there something else wrong with him?

looks burnt and over watered. medium is too compact. Angle hard to tell but might need more light as well.

Needs more water and less light

Hey 👋 Looks like you got several problems from what I can see. 1) she does not get enough light, that’s why her stomach grows such long 2) her leaves go down due to dry soil… just water her 3) leaves are getting crispy on the edges, which indicates that she is either burning, or PH is too low. Hope that helped 👊

hi Growmie, its hard to say from just the picture but it seems the soil is s abit dry and mayb SHE (i think its a she.. lets hope) has got a bit too much nutes or just too soon? seedlings dont need nutes only love and water... Or the soil is a bit wet??( i cannot see ) then the roots cannot grow and are suffacating.. then just transport her in another pot with fresh soil (not too wet)mayb she will perk up.. anywayz, Goodluck!

hopefully, it is a she... no info to go on, so you can't get much of a response. substrate definitely needs greter aeration properties, i.e. more perlite or similar. Also looks to be bad watering habits based on drying pattern but cannot be certain of that from one still image. the plant is pale because it is not being fed properly and probably related to the above mention of bad watering habits. go read guides and article (not user-submited comments) on cocoforcannabis.com. These are the best guides for growing pot with the least amount of bro-science nonsense i have ever found. Forums are a wasteland of misinformation but can glean some good stuff occasionally. be skeptical of user-submitted stuff.