Does Dyslexic Cause Forgetting Things Learnt At School?

i used to remember almost all things i used to read or listen till about a year back..but now i tend to forget things..i didn't use to even study till i was 12 or 13 but i used to get good marks due to the knowledge i got from reading books..but now i cant even understand or remember any stuff i study at school,even if i work hard.when i see the formulas and equations,it doesnt make any sense.its like i am dyslexic . please help.when i checked my IQ about 2 years back it was140,which isnt bad but its like i lost my brain capacity