Randomly spotting after sex

My cycles have been weird lately. I usually am consistently a 35 day long cycle. Now I’m jumping from 29 days to 32 days to 28 days. I also am having horrible pains during ovulation much worse than period cramps. I am spotting after we have sex too almost half the time now. I don’t know what’s going on, but my husband and I are about to begin ttc for our third baby. I have never experienced symptoms like this before and wondering if anyone else is in the same boat.