I have had unexplained nausea for 6 weeks plus..it occurs mostly immediately after I eat or drink anything. I have lost some weight, have some intermittant pain in the flank area, left and right, and also in the middle of my upper stomach. There is no way it is pregnancy!! I am 47 year old female, also experiencing burping immediately after ingesting any food...help?

Optional Information:
Female , Age: 47