sorry for reply to a really old post, but fyi, ive had the exact same problem. the reason why this is happening to you is that generics are not the "exact same", as pharmacists and doctors will tell you. there is actually a "fudge factor" written into the law that allows generic drug producers to vary slightly from the brand name which they are copying.
Shire makes the real
adderall, and the effects of its 10 and 20 mg, the only two ive tried , are about the same, very clean "speed" feeling.
the generic has some sort of binders or difference in chemical makeup which to me feels like a combo of
ritalin and some crazy street drug or something. i dont know whats in there, but its not real adderall.
adderall is a mixture of different stimulants, by design, the generic people are just making a bogus cocktail, probably to save money. im right there with you, i hate the generic....