adderall xr | ADHD Information

ok so ive been taking adderall xr 20mg for a few months now since school has started. at first it was great and changed me a lot , i felt like a much better person and a lot happier. I stopped smoking marijuana and started lookin into beter things in life. recently it seems that the adderall isnt doing much for me. im still having a hard time focusing allof a sudden and im starting to get into old habits that i stopped wen i started the medication. I also seem to be sore everyday wehn i take adderall. Its either my back or my legs and it depends how i sit in class which hurts more. Is this from the adderall also? any help would be greatly appreciated and any advice . thank you