Hmm...
A few things come to mind.
Baby could be laying on a nerve, this happened to me near the end of my first pregnancy, I had an extremely tender spot at the top of my uterus that really limited my activities and caused me a bunch of pain. Best we could tell, it was the weight of the baby pulling on a nerve. After birth, I had a numb spot across my ribcage on my BACK at the same level as the pain had been in my FRONT, but because all those nerves wrap around your ribcage, the dr suspected the nerve had been damaged or even severed, causing the numbness.
BUT, they also were worried about an abruption, which is another possibility. Anytime there's specific spot pain, that's a concern. A quick ultrasound ruled it out, also ruled out a uterine adhesion. It might be worth calling the dr to rule out something bad like that.
Is it in a location that it could be an ovarian cyst? A friend of mine had one that got much larger during pregnancy, plus the weight of her uterus pushing on it, and they actually had to remove the cyst at 34 weeks because it was bleeding.
Other, more common, things could be: constipation or gas (yes, those pains can get rather severe during pregnancy, although you woudln't expect them to last more than a day or two), bladder or kidney infection, appendicitis, gall bladder attack, pulled/torn muscle, and of course round ligament pain.
Some uncommon things: injury to the spleen (have you had anything happen recently that could have caused internal injury like that?)
My suggestion would be to just go in and have it checked, it's likely to be nothing serious, but worth ruling it out also. And, when you know that it's nothing serious, you might be able to relax some and notice your pain actually decreases because of it. The worry alone can make the pain seem so much worse!
