I have a lump below my right rib cage. no pain. can feel it more when lying on back. but it seems to be changing positions when felt at different time?

Hard to say: If you have a soft tissue lesion anywhere that you have noticed, it bears observation. Lesions that are increasing in size, especially rapidly, or those associated with increasing pain, are concerns for malignancy. A painless mass which is constant in size, unchanging in appearance, and unchanged over time is likely benign. Lipomas are the most common soft tissue benign lesions; common and benign.