Hi Shirin and welcome!
I will agree with comments above...please get in to see your primary doctor and/or a urologist ASAP! Daughter just had a bought with a combined bladder/kidney/uterine infection not long after giving birth. No idea where it came from but she had such bad pain like you described. Even though you don't have a history of UTI's it's still very easy to get them. It's very common in women and one of the leading causes if having sex. Not very fair, huh? ;-)
Anyway, here's a link I found that explains more. See if this describes what you are feeling. I hope it helps!
Moderator on the Fibromyalgia and Chronic Pain forums
“If you want to live a happy life, tie it to a goal, not to people or things.” Albert Einstein