Stray cat, odd illness

[guestmeow]

Hi I recently broke down and rescued a stray cat with the intention of doing everything within my budget to care for it. I found the cat at a McDonalds about four days ago, and have noticed signs of a strange illness. I plan to bring him to the vet ASAP after I get paid next Thursday. Until then, I would like some advice - He does not seem to be in immediate danger or in need of emergency care, but his symptoms are worrisome. As to be expected of a stray, he is not neutered and is covered with skin lesions (ringworm, flea allergy?), fleas and is missing fur. I gave him a bath and he was extremely filthy. He acts very lethargic and though he uses the litterbox, he also uses the floor and his bed and doesn't seem to have complete control over his stools. There are times when he will perk up - when he's eating, drinking. His appetite is fine, and his stools showed no signs of worms. While he is definitely scheduled for a vet visit, I was wondering if anyone knows if I'm describing a particular illness or disease. I do have a budget that I can spend on him, though I am willing to give him a chance if I find this is not something too serious, or that will cause suffering and not worth "extensive" or painful recovery time/treatment.
Thanks a bunch