Hello,
My daughter four and a half year old have just started the Exjade. She is taking same 250 mg with 20ml of water first thing in the morning and takes her breakfast 30 minutes later. We are anticipating the ferritin to go down in about six months. It is very important to continue even after target ferritin is achieved, your doctor can discontinue exjade TEMPORARILY given ferritin goes very low (but that is for the doctor to decide). Please note It is not feasible for ferritin to go down to 100 (as you suggested), the optimal level of ferritin in thalassemia major is recommended to be around 700.
It is also very important that you check her Carintine levels every week, this ensures that her kidney function is fine. If your daughter have not shown any of the typical side effects of Exjade in two weeks than chances are she is fine with the dosage, however, the green poo is not normal, I have not heard this in any patient. Please check with your doctor about the colour of poo.
I initially thought 250 mg was a bit too much to start with but it is all relative to weight of the child and level of ferritin, I am sure your doctor is ok with it.
You are doing all the things right and keep continue with it, if you have any question please post them here and the group will try best to answer it.
Regards.