Heyy, So I've Been Wearing Tampons Since I Was 10.

Heyy, so I've been wearing tampons since I was 10. I'm not 19 , I've never had any problems with it. Ever. Well recently I have been diagnosed with polycystic ovarian syndrome and was put on the depo shot. I started bleeding the day I got it done, now it's been almost a month later and the bleeding is now very heavy. Last night I woke up with SERVE vagina pains. I had a tampon in but it was only in for maybe 3 hours. Well I couldn't even touch it cause it hurt that bad. I felt like my hole was getting smaller and smaller , I finally got it out and blood poured out. Now it hurts to even put a tampon in.
And when I say the pain is a little I mean the pain is probably a 9.5 out of a 10. I just don't understand what is going on.