Bleeding DURING sex while pregnant

My SO and I were having sex and in the middle of changing positions he noticed I was bleeding I wasn’t spotting I was bleeding there was a good amount of blood on his penis and when I went to the bathroom there was more blood and I hopped in the shower and got out and still blood not as much but more like spotting at that point. I’m 31 weeks and 2 days. What should I do I stared crying once we noticed I was bleeding because I have no clue what’s wrong but when I look online everything says it’s normal after sex but I was bleeding during not after.