What's wrong with me?!

I've just stared my period literally 9 days after I finished my last period. I'm really worried, has anybody else had this happen? The period I had 9 days ago was horrendous! Literally had be crying and vomiting with the pain! So I'm confused as to why I'm bleeding again. My GP was very dismissive of it too so now I'm just sat panicking lol having really bad cramps in my stomach and lower back too.