adderall and gastro problems?

[yessir6666]

i woke up this morning and took some antacids (tums) and then about 5 mins later swallowed 2 whole 20 mg adderall XR's all on an empty stomach for studying purposes. about 40 mins later, without getting too graphic, i have an enormous ammount of diarrhea every 10-15 minutes or so. is this caused by the adderall or maybe the antacids? and my biggest concern is, is all the diarrhea causing me to expel some of the amphetamine without it being absorbed? im not sure if thats possible, but im beginning to think so because 2 20 mg xr's don't even really get me stimulated, although i might have a high tolerance. all your info is greatly appreciated, thanks in advance.