Could I be pregnant???

I'm on the mini pill and I take it the same time every day, I've been on it for 4 months now and haven't missed one apart from back in the first month. My boyfriend came inside of me about 2-3 weeks ago for the first time and I have now got such a bad lower back, tummy cramps and feel sick sometimes and I also had spotting a few days ago!! What shall I do??