Welcome to PC House123!
I hear your frustration and too can relate. Between the symptoms themselves or med changes, both wreak havoc on studying and focus. Despite being a good student, because of my symptoms, I had to reevaluate my study habits and to learn to accommodate them. I couldn't do things the way I used to as it wasn't working. It took working with counselors, pdoc, and tutors to learn a new way of going about things, to get a different perspective, and to get back on track. It also helped working with the office for students with disabilities, and with an with an ADHD diagnosis is more than likely can qualify, just need documentation from one of your providers. There can be help with notetakers, testing, etc.

In the meantime, talk to with your professors about what is going as most are understanding; they can help with either suggestions for additional resources, leeway for extra credit at times, and possible extensions if it comes to that.

You are a good student, you just have some obstacles that need rearranging at the moment to help you succeed. Use the resources that are available: talk to your providers about techniques and tools, find tutors for a different way of looking at the material, talk to your professors in the meantime and let them know what all you are doing and ask for suggestions, contact students with disabilities office, etc. Help is out there for the asking. You can do it. The best of wishes meantime and hang in there.