Cramps as a withdrawal from pill or pregnant?

So I've been missing a lot of pills. I had sex a little over two weeks ago, after missing two pills and I had started to have breakthrough/withdrawal bleeding that day. It lasted about two days so I assumed it at least meant I couldn't get pregnant. I tried to get back into taking the pill after that, but then a week after the sex I had gotten brown discharge that would go on and off and lasted a few days. I finally have decided to just stop the pill altogether as it's clearly not working for me..Now I'm getting cramps / lower back ache and lots of clear & white discharge. Idk could that cramps be from stopping the pill? Or should I be worried about being pregnant even though I had sex while bleeding and had the brown discharge later? I should've  been more careful but now I'm just wondering if I should take a test or just assume it's the pill and how bad I am at taking it that's messing with me.