A HIDA scan is a nuclear medicine test that tests the function of your gall bladder. Basically, you will get an injection into a vein of a radioactive material and then just lie on a table while a large square thing scans over your abdomen. It will not touch you and it's really not big enough to cause claustrophobia. The length of time the test will take depends on how well your gall bladder is functioning and how long it takes it to contract and empty.
Piece of cake.
For the upper GI/barium swallow, you will begin standing in front of an x-ray machine and the radiologist will give you barium to drink while he takes pictures. Depending on the hospital, you may be asked to swallow some crystals before the barium which will fill your stomach with air. It's important to try not to burp so they won't lose the air. Then when you drink the barium, you will lie down and roll around a couple of times to get your stomach coated with barium. The radiologist takes a few more pictures and then usually the techologist will also take some.
Also, piece of cake.
Good luck and I hope they figure out what's wrong.