What Causes Pain In My Back And Legs During Period?

A bit of history: I have always had difficult periods since my first period at a late 17 years old. They are always irregular and very painful. After I had my daughter 9 years ago they became quite terrible, sometimes lasting 2 weeks. The pregnancy itself was very difficult as well, I had toxemia.

My periods will start off with painful cramps 2 weeks prior, and then I spot brown blood for 2 days until it changes to dark red. Normally mild lower back pain is involved. This can last anywhere from 7 days to 2 weeks. My doctor told me that this was normal for my body. I normally take 2 Aleve in the morning and am good for the day.

My husband had a vasectomy 3 years ago after I had a 2 miscarriages in 10 months. He has been checked, there is no way I could be pregnant.

I am 31 yrs old, 5'5", 115 lbs. I jog 3x a week, go to a 1 hour yoga class every other Saturday, and eat fairly healthy with the occasional sweet snack. I do not take any medications except for Aleve to relieve the pain, and Claritin for seasonal allergies.

My question is, last week, I had thought my period was starting. Had cramps & lower back pain and bled bright red blood for 3 days. It stopped on Saturday. Then two days ago, I started getting severe lower back pain with cramps and bloating. Yesterday, I had a blot clot the size of a quarter and the back of my thighs started hurting. Today is all the same symptoms, but I am developing a low fever of 100.7F. I am not really bleeding at all, but there is a small amount of dark blood on the tampon when I take it out and it has an odor. Not discharge and not a fishy smell, just different. The pain in my back and legs has gotten worse as well.

I called my doctor and he can't see me for a week. What could this be, and do I need to go to the ER or can it wait a week?