TERRIFIED BLEEDING A LOT

I put a new tampon in 45 min- an hour ago after a huge (looked like I peed myself with blood) leak. I suddenly felt like I was leaking again and all of this (and then some) came out. JUST 45 MINUTES AFTER I CHANGED TAMPONS AND COMPLETELY WIPED OFF...why so much blood? I'm terrified I'm dying. Everytime it happens I get really dizzy... 1st real period day (spotting yesterday). also super nausea and headache (but could be food related as I ate candy today and I usually don't) I have an IUD and I think it's still in place but strings have been harder to find lately.

**We're in the middle of a road trip so ER isn't an option***