Hun.. I am really sorry to say this..but this doesn't sound normal. not only could it be a m/c, but maybe an ectopic pregnancy...I would suggest you go to your doc or ER ASAP. This could also be caused by a cyst that rupture or even a fibroid. I do hope you find out what is going on and get better soon...let us know how it goes.
PS...Just in case, you shouldn't tampons.
What an uncomfortable event, I'm so sorry you're having to experience this!
Your symptoms do sound like my most recent miscarriage. You really should call your dr. or midwife and get into one of their offices, because miscarriage or not, you're having something go on that is unusual for you. if it is a miscarriage, there is nothing that can be done at this point to save the pregnancy, but at least you'll be monitored for signs of infection.
Best to you.