Period-like bleeding after sex

Alright so me and my boyfriend had intercourse about 2 weeks ago, and in the middle of intercourse I started my period and continued to bleed for about 5 days, it felt like a period DEFINITELY and after 5 days I thought it ended and I continued to have protected sex with my boyfriend. Well, 2 days after I thought my period ended I ended up bleeding bright red blood and i continued to have bloody discharge for the next day, 3 days later after that I only spotted a little bit and maybe 2 days later again, we had intercourse and I didn’t bleed at all. Well, I thought this problem was over and that I could go on with life as usual but today we tried to have intercourse and I bled bright red blood and it’s a very substantial amount (like I should be wearing a panty liner at least) and it’s thin blood and it isn’t really exactly like the bleeding I do on my period but there are clots and it’s quite an amount. I’ve never had this problem about bleeding like this and my uterus feels like it’s cramping like when I have my period. I’ve had protected sex with my boyfriend entirely and i haven’t had a previous partner since about 10 months. I’m just wondering really if this has happened to anyone and if I should be worried or not, I plan to get it checked out if it persists. I’m just concerned because I’m not experiencing any STI symptoms and everything feels fine, and pregnancy is very unlikely because I’ve only had protected sex with condoms and avoided doing anything before or on ovulation. I’m suspicious this could just be my period being triggered by my uterus contracting during intercourse but I’m not entirely sure that is a thing. If this or something similar has happened to you please let me know