My friend experienced the same thing. After her daughter was born she was incredibly sensitive and found that after sex she was crying, it got to the point where she didn't have sex as she knew it would be so painful afterwards.

Did you have an epistiomy? If so it may be that the incisions have over-repaired themselves, leaving a raised area within the vagina that can be sore and cause pain during, or after sex.
If this is the case a simple procedure know as 'Fenton's Procedure' may sort out the problem. In the procedure, this scar tissue is cut out and then the edges of the new incision are placed together and re-stitched. It is normally performed on healed tissue so you may have to wait a few months before you can have the procedure performed.

This may not be the problem but your situation does sound very similar to that of my friend's.

I would definately see a doctor ASAP just to make sure everything is ok. My friend got cervical cancer at 23 and had to have a radical hystorectomy after her 2nd child. Each time she would have sex she would bleed like on her period and have severe pain. This is a lot different from your symptoms, but she didnt think anything of it. She just blamed it on the recent birth.

Did you have a c-section or a vaginal birth?

to respond to your question I had an vaginal delivery. My doctor said the pain was from lack of estrogen in my body from breast feeding and that when I stopped that the pain would go away. He said the lack of estrogen make the uterian lining thin and prone to swelling and that is the pressure and pain I feel. Well I stopped breast feeding a month ago and still have the problem.....!!!

My baby is nearly 9 months old and I am having painful intercourse. I had a traumatic delivery with much tearing (no episiotomy). Then, after 6 months I had a surgery to remove the scar tissue called a "posterior advancement flap". Even though the original stitiches and tearing from delivery healed beautifully, I till had pain...not only during intercouse, but sitting, bending, walking, wearing snug jeans, etc. The surgery went well and we have resumed sex. It is still painful, but the doctor assures me that having frwquent sex is the best remedy because the area needs to be stretched. It is so diificult to look forward to sex when it is painful . Entry is painful, it gets better after that...but I can be sore for the next day or two. I am giving it a god try...am resentful that I have to go through all this...but am happy that my husband and I are having sex again after nearly 9 months (plus part of pregnancy). I just want you to know that you are not alone! Many of my friends say that it takes months for it to feel like it did before. I've also gotten the advice that you should not wait too long between the times you have sex (which goes along w/ my doctors advice).