Whats wrong with my little plant?

It seems your following a feeding chart for photoperiods & your growing an auto. These do not need as much feed. I'd flush with ph water & when dry, use just a 3rd of the recommended amount. Good luck

Either you got solution on the leaves, and it dried or it is possibly TMV.

From the words of wise IT professionals poor information in poor information out. Without knowing what you fed(amongst other info) her we cannot give you any accurate answer. Start a diary it's fun and there are great contest every month.

It appears as if you have a bit of salt buildup on the edge of your pots just above the soil line. Unless it is diatomaceous earth. That may be an over feeding issue, potential nutrient lockout, PH issue, or a nutrient deficiency. It is hard to say with out much more information. A diary would also be beneficial. Hard to tell from a picture but they look a bit dry. Have they been watered recently? Underwatering can lead to a deficiency all on its own. PH - get a digital Ph Meter on amazon they are about 15 bucks. Ph Should be around 6 to 6.8. Watering- If they havent been watered water them. Nutrients - If your feeding them synthetic nutrients cut back or stop for a bit. ( I recommend compost or castings as organic alternatives) You may need to take the plants out and clean the pot then put the plant back in if that is indeed salt buildup.. Then flush any excess nutrients/salts out of the soil. You will need to feed them properly after the flush.(again organic is a great option and hard to mess up) Deficiency - check to see what nutrients the product you are using may be lacking. Seems to look like a calcium issue. Try checking there first. This is much info as I can give you without more info. Hope this gives you an idea of where to start. Happy Growing.😀

Without a diary it's impossible for us to tell you what's wrong with your plant as we have no idea what you're feeding it or when. That said, using the pictures you've added as the sole source of information, it looks to me like a virus... specifically, Tabacco Mosaic Virus - https://www.growweedeasy.com/cannabis-plant-problems/tobacco-mosaic-virus-tmv. As far as I'm aware there is no cure for this and you're fine to continue growing the plant if it looks otherwise healthy. There is a chance it can be spread to your other plants though. Hope that helps! Please add a diary and add a list of all the nutrients you're using and we can have another look.