i am on depo provera birth control shot and..?

ok here is the issue I don't know if its linked but here lately I have been getting light headed and it makes me sick to my stomach but it gets better when I eat something like crackers or any solid food or like a soda, but that's not it im peeing a lot and I just had the first spotting could someone tell me what is wrong? I don't have a period because I am on depo. is something wrong or is this normal.