Start with the counseling center. Some focus problems are related to emotional health and it sounds like regardless of what is going on, that could help. They may refer you for a neuro psych exam (which sounds like a good idea in any case.) Your mental health state will be important to interpreting the results, which is why you should go down both paths.
If you want to use some of the strategies for ADD sufferers, you’ll find them helpful (whether you have ADD or not.) Breaking tasks into smaller pieces, getting rid of distractions, taking brisk walks between tasks, etc. You can try drinking coffee water while studying (or a cup of coffee before you sit down). It helps some people.
But the big takeaway here is Seek Help!