Over the last ~4 years I have knowest my intelligence is inconsistent. on some days I'm quite sharp while on others I made stupid mistakes (such as forgetting a basic step-by-step procedure among other things). normally I'm in a middle ground (60% of the time)

details about me.
-male and 18
-trouble concentrating,spelling,motivation...
-not on prescription meds or anything. I'm pretty healthy
-***shows symptoms of ADHD and Dyslexia (never felt need to get tested)***

please let me know what you guys think I may have and what I should do about it.
Thank you in advance.