Google the meds you are or were on with the term 'side-effects, lack of concentration, memory loss' and any other related symptoms and see what you find.

I was on psych meds for 13 years, and now have very poor focus and concentration. I also was an avid reader like you and now find it takes me a long time to finish a book unless it's the most fascinating thing I've ever read.

Look up Gwen Olsen on youtube and watch some of her videos on drug side-effects. She talks about how antidepressants lead to memory issues similar to stroke patients where you can't find word [I have that too] among other things. These meds aren't nearly as safe as Big Pharma would have you believe...