Today I Woke Up With Pain In My Left Upper

Today I woke up with pain in my left upper quadrant, sharp. It is also accompanied by lots of belching, not necessarily both at once. I just had an upper gi scope and nothing is wrong they said. When do you know to go to dr. If i sit up its better, not totally but it really helps. If i lay down it pains so bad i need to sit up. Any ideas? Thanks