I went through this for a while when I was suffering with thyroid disease. I couldn't remember anything. I had to bring a notebook everywhere I went just to take notes. Routine things also like forgetting to do laundry or what my own phone number is. It got very frightening.
I bought a shirt with a pocket in it (like a nurse's top), and also an apron so I could intermingle them during the week. I kept a pen and paper in my pocket at all times.
I also had a calendar I would write appointments in, and a white board on the fridge for things like that. I also wrote important phone numbers in my calendar so I'd have them quickly if needed.
I started taking a few vitamins. Ginkgo, plus some Korean Ginseng, Vitamin D3, Magnesium, and Vitamin B. That really helped a lot.