UGH! What is wrong with my baby?

So I've been researching and reading for like a week now, and I can't figure out what the fuck is wrong with my plant. It doesn't look like anything described, over/underwatering, over ferting, etc.

I'm growing outdoors, in soil. I don't have a particular watering schedule I just water when the soil gets crusty, I've been feeding with Miracle-Gro Houseplant food(I know, I know, not the best fert but my boyfriend insists on using it...)
This is my biggest plant, about 18" tall before I LST'd and it has been like this for at least a week and a half!

The leaves are curling under and getting shriveled and now the leaves that are on top are turning super dark green, not like normal pot plant green...

Pictures( I know they aren't great but cut me some slack I had to use my MacBook, someone broke my digital camera...)

Maybe they are underwatered?

I highly doubt that, although I guess I wouldn't rule it out, because this problem kept occurring even after I soaked the shit out of my garden. :/

Anyone else? Another thing I forgot was I used Sevin Insecticide on them, it says is vegetable and fruit safe.

water it more and feed it less. dont let the dirt dry up.

That's the thing though, like I said, I doubt it was underwatered because it was having this problem even when I soaked the shit out of it.

how is your soil? drainage? it does look like underwatered. i use MG, so don't think its that, unless your using a weird one, meaning the Tomato one. i am using that now because i need it during flowering. usually for vegging i use the standard one.
love your avatar by the way.

Not sure how my soil is, the garden was already established when I got here, and I didn't really even think these seeds would grow. They were ones I was germinating and then they dried out, and then I spilled them all over my patio, so I just threw them in the garden thinking "hey if they grow, great, if not oh well"
No I'm not using the Tomato miracle gro it's the Houseplant one and if I remember correctly it's an 8-6-7 or something weird like that. What does that mean?

you need a higher first number for your starters but not to use nukes until at least 3 weeks old. i look at it like this, the 1st. number is for the top of the plant, the leafs, the 2nd. is for the general growth of the plant and the last is for the root system. that is the easy understandable way for me . others are gonna give you a more detailed explantaion. but for me this is my way.some use a 16x16x16 fert. which is a general purpose.
then when you flower, you need to change to a high middle and low nitrogen which is the first #.all in all, it is what works for you and what you can afford.

Something is going wrong with them hard to tell with the picture but looks like some marking on the leafs edges. With whats stated before maybe get something with a little more nitrogen and see if it helps them. looking at this link https://www.rollitup.org/marijuana-plant-problems/216537-self-diagnose-your-plants.html
It looks like the begining of nitrogen deficient. Since the leaves are clawing down. But very hard to tell with the markings on the edges of leaves and not the whole leaf itself. Hopefully you can trouble shoot it by using the link I provided.