Michelle,
I'm glad to hear that your mom reached remission.
There is a detailed description of Exjade (deferasirox) at
rxlist.com and it's not hard for us laypersons to read. You didn't mention your mom's age but MDS patients age 65 or older have adverse reactions to Exjade more frequently than younger patients.
Mild to moderate diarrhea is one of the more commonly reported side effects of Exjade. The manufacturer (Novartis) reminds patients to drink fluids. But this may be more than "moderate". I think that you or your mom should talk to the doctor about it soon, if you haven't already, in case the dosage ought to be changed. If she needs treatment for iron overload there may be a tradeoff of risks.
I haven't read about Exjade affecting platelets (there were some comments about it in our
External symptoms from MDS? thread, but very low platelets are a possible contraindication for Exjade. Whatever the cause of the platelet drop, if they get much lower your mom may not be able to continue taking Exjade. She made need another CBC test to establish what the trend is.