Possibly skin issues?

Hi, first time posting and I hope I'm doing this right. I rescued my boy about 3 years ago now and we've gone from fleas and ringworm to crystals and being blocked. Recently I found a spot under his chin that looked like he scratched himself. Every night I cleaned it and put some ointment on. Seems to be scabbing up and getting better. Today I noticed he has a spot of dark, scaly material between his shoulders. Both spots do not bother him enough to be disgruntled when I touch or hover over them. If I did this right, I've attached pictures (first day of scratch, scratch today, patch). I'm struggling with his last $3k vet bill so any answers I can find here are gonna save us big time. Thank you.

I honestly haven't got a clue what that is. My first though (because of the shape) is ringworm. Having said that, I really do urge you to get him checked out by a vet. I know money is tight, but online advice is no substitute for veterinary treatment. Those patches do look sore, and there's always the risk of infection if you delay treatment. Please take him to a vet.