I have had a pea sized lump under my right rib cage for the past 2 years or so. When i first found it, i got a ct scan and the doctors said they saw nothing, but to come back and get checked again. I never did. I am 16 years old now and today i noticed a sharp pain coming on and off underneath my right rib cage. I then remembered about the lump, and when i went to feel it i noticed it has gotten bigger. I also looked up possible causes of this lump and saw that it could be liver or kidney cancer (i can't remember). Anyways i saw that another possible symptom could be pain in the right shoulder, which i have also. What do you think it could be?