advise please

for a few weeks or so now when me and my boyfriend have sex it becomes almost uncomfortable after a little while and sometimes we have to stop, i will then go to the toilet and when i wipe, light browny coloured discharge is what i see on the toilet paper. does anyone have any advice on what it could be? / anything we can try to see if it helps.

could it be i’m not staying lubed up enough during actual intercourse? i don’t think it would be that as we always do a bit of foreplay before we fuck and he always makes me come multiple times.

i did have a bad experience with getting the coil fitted which has caused my pelvic floor to tighten so could that maybe also be causing the problem?

thank you.