Why do some people experience headache, giddiness, and forgetfulness while studying?

Hi doctor,

I have had an uncomfortable feeling in my head for a month. I feel symptoms like a slight headache, mostly on the right side and around the front side sometimes, it feels hot and burning, and I also feel giddiness, heaviness, and forgetfulness. But those symptoms are not always happening or severe. It happens whenever I study or memorize words for a long time. Because memorizing English words is what I used to do for the past four to five years, and I have memorized about five thousand words within this period.

I will give here some reasons that I suspect to be the cause of this illness :

Before this illness, I wore glasses without testing their power and was not prescribed by any doctor. I feel giddy whenever I wear these glasses and have a slight headache. So after some days, I stopped using it.

Before 50 days, I had a fistula surgery (fistulotomy). Because of that, I took antibiotics, painkiller courses twice, and other medicines. After the surgery and again after the replacement of the seton, I took the following medicines:

1. Tablet Linid 600 milligrams once a day for seven days.

2. Tablet Metrogyl 400 milligrams thrice a day for seven days.

3. Tablet Combiflam thrice a day for three days.

4. Capsule Bravia IT once a day for seven days.

5. Tablet Disperzyme thrice a day for seven days.

6. Calcigrand Forte once a day for seven days.

7. Capsule Quvast once a day for seven days.

I have high blood pressure and have been using Telma 20 milligrams once daily for the last two years. I am also a diabetic patient, but as of now, I am on the borderline and can keep it under control by diet and physical exercise without taking any medicine.

Kindly explain whether my head problem could be any of the above reasons. Or if it may be because of other reasons, kindly explain to me what may be the reason and what I should do to diagnose or take care of it.

Thank you.