Something wrong with my stomach?

Ok so in April i went to the hospital to get my apendix removed and went home all fine. After two weeks i started having more pain in my right side so i went back to the hospital and they took a catscan and they just said i had something inflamed and gave me some pills to take.3 days later i stopped eating and lost like 20 pounds then i went back to the ER and stayed there for days then went home they gave me a appointment to go to in a week, Yesterday was that appoinment and they did a ultrasound and they found a black ballish thing in my right side. they sent me home telling my mom they would call her today and tell what it is. They havent called yet. does anyone know what this thing could be? I just wanna know im nervous and scared so yea please answer quick. Thanks Alot!