Bad cramping after sex

I am 29, married and otherwise healthy. For the past week in a half after my husband and I have sex I've been having some pretty bad cramps. It's gotten to the point to where I can no longer lay on my stomach to sleep and the cramps will go into the next day. The worst of it is on my lower right side near my hip bone..it feels like someone is stabbing my hip bone when I sit down or stand up. We do not have rough sex so I know that can't be the reason. It's never done this before though so it's starting to worry me. I've also been having hot flashes(too young for menopause), fever on and off, and I haven't been sleeping too good at night. My last menstrual cycle was the 2nd of this month and it was actually kind of strange. I have a 28 day cycle and normally only bleed about 4 1/2 days. This time I started a couple days early..it was heavy for the first day in a half then light. I stopped bleeding at day 5, started back day 6, off again day 7 then spotted brown(a small amount)the next 3 days. I've never done that before either. My periods have ALWAYS been the same. ANy help and/or advice would be greatly appreciated!!!