Wilting/ leaves turning in and turning dark.

Hey I'm 100% new at growing, I masterd mint, potatoes, and tomatoes... but Bud is on a different wave legnth. I understand my growing method is certaintly not recommended but certain circumstances have left me with this option.
I use sun light (early morning untill night) (untill I get £, for a lamp)
Miracle Grow soil (stuff we had left over)
And the seeds I got from a Ten bag (1.0-1.2 gram= £10) so it's an unknown strain.

Untill they started to wilt they seemed to grow well, they're roughly 1week and 4-5days.
The smallest (youngest aswell) only recently wilted, and the two oval leaves are turning inward and going a darkish colour.
The oldest, and biggest tilted about 2days ago with no disfigurement to the leaves.

I've thought of weak stems, over watering, and even disease?

I will have to add photos on a later day as again this phone fails me.

Hope the information I've provided is descriptive enough?

Thank you!! :')

Oooh... please save the "douche bag" post, the plants are already shouting it at me!