Sharp Upper Abdominal Pain

Starting a few days ago I noticed a slight pain in my abdomen about half way between my belly button and my chest. Since then the pain has gotten increasingly worse.

It's an extremely sharp pain in the area described above, and it's close enough to the surface that it could probably be mistaken for a severe muscle cramp, but it's not.

If I sit up, it feels alright. Laying on my back or stomach feels like someone has stabbed me, and laying on my side still hurts significantly, but is the only position I can fall asleep in.

Last night the pain peaked, but when I woke up today it had died down a bit. Now my entire abdomen feels bloated though. I have had no indigestion, and feel perfectly fine other wise.