What could this be..? Maybe TMI

I got my first depo shot around the first week of March and I've had no complications with it so far, but about 4 to 5 days ago I started lightly spotting brownish blood. I thought "oh well, this can happen" well each day since then it's gotten a little heavier and it's bright red now and yesterday I noticed blood clots (I guess?) Instead of just blood. Today I started cramping and these past two or so days I've been nauseated. It kinda feels like I'm on my period. I have a doctors appointment tomorrow afternoon but I was wondering some thoughts? Should I be worried? What do yall think?