Have you had your thyroid checked? I used to have 20,000 different problems (ok, I'm exaggerating a bit, but I had a lot of problems). I was told I had everything from Irritable Bowel Syndrome to hip dysplasia, all supposedly unrelated. Many were just chalked up to getting older. Well, you're over 40 now, that's what happens! Otherwise, I was in "perfect health."
I say B.S. I know people in their 70's who were in better health than I was!
All my myriad of symptoms ended up being due to one problem, hypothryoidism.
Among my many symptoms were "brain fog" and poor concentration/memory and depression. Since I've been on thyroid meds most symptoms are gone.
Something to look into.