tmi but im new to sex & have a question

KJM • Hospitality Industry Professional, Mom of One, Still Figuring Out Life
Iv been having sex almost 3 months with my fwb who i lost my virginity to. This last time we had sex on Thursday for 5 hours. I squirted for the first time (which i said i never wanted to do but oh well)& did it 9 times in total. Anyways he kept pulling his dick out of me & very violently shaking it back & forth on my vagina. I know for a FACT he wasnt cumming because he only ever cums in me but my questions are:
Why does he shake his dick so violently there? Is it to make me squirt more or..?
I have soreness in my bones where the skin of my thigh meets my butt meets my labia is this because of how violent he was hitting his penis?