GIRLINNEED ,
but how many ppl has he been with, sex comes with baggage sometimes, if that person has had sex before and you havn't , you are exposed to all the viral and bacterial std's he may or may not have known about.
protect yourself until the day you know, that he is the one. i have seen to many girls whom have been taken down a life altering path because their boyfriend did not want to wear protection.
Here is the honest truth, if he loves you, he will.
Also you are complaining about pain in your lower back, this could be a kidney stone to a eptopic pregancy, just because your on the pill does not mean you cant get pregnant.
I would continue to see your physician and maybe ask to see a specialist if she does not relieve the problem, as a doctor i get red flags when anyone says backpain, stomach pain, chest pain. all of these area's our vital to our bodies survival. make sure you keep taking care of yourself.