I've been on 20 mg Adderall XR for several months now. It works just fine. However about one day a week or so, I get an AWFUL headache, centered behind my right eye. It lasts all day.

I get migraines but I always have the visual "aura" with it so I know it's coming. (and I've only had one migraine since starting the meds) I don't have an aura with these other headaches. Anyone else experience this?

Sounds like either sinus problems or "cluster" headaches (which are caused by muscle contractions). If you don't have any reason to think you're more tense than usual, you might look into sinuses.

I get these headaches, too, when Adderall is wearing off (but after several months I doubt it's suddenly doing that for you), but I also get similar headaches when my sinuses are acting up.