I take femara too and dizziness is one of the side effects listed on the product information. If may not be as common as some other side effects but if the maker lists it.........
I’ve never had that problem myself but clearly it can happen.
The binding agents used in pill manufacture vary, although the active ingredients remain the same for different brands of the same medication. If you are sensitive to lactose for example,a brand with more lactose in the binder may cause a reaction (to the lactose not the prescribed medication). It may be worth trying another brand, just in case but worth discussing again with your oncologist. Best wishes.