Thanks for posting on HCM,
Now, your situation might need some careful analysis before concluding that you might IBS or not. Looking at the two medications per say (with respect to their side effects), you can note that xanax (alprazolam) has as digestive side effects to be constipation
(10-15% of consumers), diarrhea
(10-15%), dry mouth
(10-15%), anorexia (20-30%) and note that this is found when taking xanax 4mg dose mean while the effects of diarrhea, constipation, and nausea/vomiting (20-30%) when taking xanax 10mg. Your previous diarrhea episodes might have been as a result of taking xanax and not IBS.
Looking at adderall XR, you may have abdominal pain
(11-14%), loss of appetite (22-36%), diarrhea (2%), dyspepsia/indigestion
(2-4%), nausea (5%), vomiting (7%) etc. You can see that both medications prresent with side effects that might be responsible for your present symptoms rather than IBS as you suspect.
So, you will need to discuss this with your prescribing doctor for alternative or prescription of medication to take care of the side effects. OTC laxatives could help but you need to be sure if the medications are the culprit or not.
Hope this helps