Blood after sex

Ok so, my period went away 2 days ago, so today I had sex and I didn’t bleed but my boyfriend went down on me afterwards and he told me I was bleeding, not a lot but I was, and then I’m like ⁉️ so then we stop and we go on with our days, afterwards I go pee and when I clean myself there’s blood mixed with my pee and I do not know why. Does anybody know?

Just in case: it wasn’t my 1st time having sec therefore I don’t think it was my hymen breaking