I can't eat food with a lot of seasonings, or really greasy food, or drink soda without feeling really sick. If I drink water and eat bland foods I feel fine though. People keep telling me its my gallbladder causing problems, is that right?

Belly pain. You can have "gallbladder pain" from typically eating lots of greasy foods. Mainly food with high fat content. The soda or seasoning maybe signs of gerd/gastritis/ulcer although there maybe overlap. You may need lab testing and diagnostic testing. Try avoiding food triggers if able.
Need to see doctor. The symptom you have could be several possibilities. Gallbladder just one of them. I recommend you need to see your doctor to get a complete check up.