ROTTEN MEAT/FLESH !! 😷😷

Not really sure how to start this off but my S/O and I had unprotected sex on the first day of my period and ever since then my period has smelt so bad !! When I pull my tampon out it smells like rotten meat the smell makes me want to gag ! I've been so nauseous lately and throwing up . I've never ever had this problem before and it's only brown/really dark red blood but it's only very light and I keep my tampons in for 4 hours max  . Has anybody ever had something like this happen to them before ? I'm seeing my doctor Wednesday but I just need something to put my mind at ease 😩