Painful sex... Help

My boyfriend and I have been having sex for 3 months now and the sex is still painful, around month 2 the sex felt fine but now all of a sudden it hurts again! It's not excruciating or anything but it's not very comfortable either! I know it's not from a lack of lube because there's plenty of that and I'm not nervous or tensed up when we have sex either. We use condoms regularly and my boyfriend is a little bigger than average. I hope all of that info helps! I don't even know how to make it feel better!