Tldr: My boyfriend is a virgin and we did it for the first time, next day I have pelvic muscle pain.

My boyfriend and I had sex for the first time. I've had sex before, but he hasn't. We went through the awkward how do we position ourselves. He's 6'0" I'm 5'3", at first he didnt fit all the way in, but after more foreplay he was able to get it all the way in. He was a good length, but a very girthy size. We got through it, but the next following day I start walking and I can feel pelvic muscle pain. Its the same sensation when I just finished working out with hip abductions at the gym. Any advice about this?