Wish I knew your age. I read your query; I do not finding any alarming concerns.
1. Low memory power - You probably need to do some mind exercises - play Sudoku, crosswords, and math games.
2. Sleepy in daytime - Seems like there is a lack of interest or failing interest in life activities. Recheck your daily schedules and the work you do. Try to add in a new hobby, a new creative project. You will stay awake then.
, etc. - Your general immune status may be dropping to a low level. Eat healthy and nutritious, lots of fruits and vegetables. Take multivitamin
supplements for a month or so.
After these, get a routine blood count done to see if all is normal. If infection is confirmed anywhere in your body, a course of antibiotic will cure it.
I do not see a problem; you seem to be healthy. Just a bit on the lower end though.
Consult your Primary care
physician for a routine physical examination.
Hope this helps.