Spotting after sex & TONS of pressure @ 37 weeks

So, my boyfriend and I had sex this morning, after I noticed some spotting, which I know can be normal! I rang my OB & asked her if there was anything I needed to watch out for & if I needed to worry if it lasted for a certain amount of time. She told me that if I’m not bleeding like a period, all should be fine & told me the spotting can last up to 36 hours. But I’ve had pressure in my bottom as well as my vagina, which is progressing more and more & a tad crampy. My question is, has anyone experienced this and all be well?