Asking for a friend

A friend of mine has not had her period for the past two months. She had taken two pregnancy tests and which both came back negative. She is also on birth control. She is not suppose to be able to have kids, but has a son that the doctors had gave her some kind of shot and did something else (I forget exactly what) in order for her to conceive. She is always tired lately, either always hungry or not at all, goes to the bathroom more, tender breasts and husband says they look larger. Plenty of pregnancy signs, but again on b.c. and not suppose to be able to conceive. She is going in for blood work, but any tips on what might be going on with her?