I’m confused.

Okay so I am on birth control which is the nexplannon arm implant. I got it back in July and for the past couple months it has made my period come and go every other week so basically two periods a month. And now it’s had been three weeks since my last period and for the past few days my back has been hurting all the way up to my neck, my left hip feels like it’s being pushed out and constantly pops painfully, I’ve been super bloated and always hurts to touch, my lower stomach feels like it has cramps but they stay for a longer duration and I can never find a comfortable state, I am always getting nauseated after a meal or between meals to the point where I have to stop eating, and tmi but sometimes diarrhea. My boyfriend and I aren’t taking the precautions we should to avoid pregnancy even on the birth control and he does finish in me all the time. I really don’t know what is going on and I just want someone to give me some answers on what I should do or something. Should I be worried. Am I okay? And plus everyone is telling me that I look wider or that I have gained weight