Not likely. Abdominal side effects from medication is very common, and usually near the top of these lists. It is not a common one with this medication. Abdominal pain, in general, is caused by distention of intestinal wall or spasm of the wall. The number of causes can fill a book. To complicate it, 'referred pain' means the pain is felt distant from the source. E.G. Chest pain may be felt in the gut.
No. Not a direct known side effect. Ask your doctor if switching to another medication or further work up is needed.
No. I am not aware that this treatment for advanced breast cancer causes abdominal pain. I have had several patients on this medication and have not seen this side effect.