Have you sought services through your college?
I know at my university a student can get some type of insurance through the university to help with medications and the like. You might want to try seeing if your Health Center, Counseling Center (if your school has one), or Office for Disabled students has any information that could help you out.

I'm in a similar situation--struggling with college work due to not being able to concentrate. I'm pretty sure that I have undiagnosed ADHD. Right now I'm seeking out my options and hoping to get tested for it soooon.

Best of luck to you!