Stray overlicking its paws and wounded as well.

I have no prior knowledge on taking care of a cat but ive been seeing this dude for a month-he is a stray,i feed him once a day-catfood (grain zero) because im only free during tht times-like 7-8.30pm-i bought that for him and other strays in our area,open to different food suggestions too.Im a student so idk if i can afford vet charges or shelter as well because of my parents,they don't want him inside our house.

The Problem is,i see him scratching himself often against walls,sharp edges and turning around showing his belly and again turn again turn like idk it looks unusual,i thought he was showing his belly to me so i scratched his belly and got two claw marks from that day i always go for his chin and ofc he enjoys it but then he often turns his body around anf around scratches himself. And you can see those wounds he often licks it-like overgrooming that area.

Not gonna lie im scared too whenever he playfully touches my hands with his paws-i could feel his sharp nails,sharp enough to pierce through my skin. So idk if i can put him in a cage taking him to vet all that seems hard for me. Please tell me what sort of wound it is and is there a medicine out there that i can buy without vet suggestion. Also,after i feed him and pet him i go to the house gate without looking him back-when i look back he meows at me and wants to stay with me-follows me,even if i stay an hour with him its not enough for him. Am i making his life more depressing and sad by feeding him once and being with him only for half hour-one hour.