What is this?! Help!

Maggie
So I recently had my appendix out and I used to be really good about my birth control but lately I've been kind a like on and off of it not taking it as well just because of my appendix coming out and now I have to get another surgery so I've just been kind of bad about my birth control and it's a bit about probably like three weeks or four weeks since I've taken my birth control I took one pill the other day but I ended up getting the stomach flu that night so that pill doesn't really count. So I would say the last time I had it which wasn't even really it was more of just bleeding a little because that was a few days after I stopped taking the pill was the 21st .. I'm not pregnant it's not even possible. I'm just curious if I'm feeling all these cramps and uncomfortable stomach pains because my periods are off and I'm off my birth control?? Sorry for how long this is!!