from reading what your doing you should specify to us what kind/brand of soil your using. did you change that light? if it is a incandescent grow light you should still change it cause it doesn't provide enough lumens and another problem is environmental heat issues. also did you add perlite to your soil? it looks like white little rocks or in some cheap soils it looks like styrofoam. if you dont have enough perlite you could be suffocating your roots causing it to wilt like that also. do you have proper ventilation and a fan circulating the air in your grow area? those are some basics you should look into. to get some brief knowledge and if some terms on this forum is too new to you, you should search "cultivation marijuana" in youtube or "Jorge Cervantes". those videos help alot. you can also download them off the net. Jorge Cervantes - Ultimate Grow is a great vid.