Hello! Thank you for the query. This lump is lipoma indeed. It probably has nothing in common with your pains. You should know that some diseases can coexist and this can be only a coincidence that this lump is in the same localisation as pain. Described by you pain is very characteristic for gallstones. The pain usually starts after a meal (usually a fatty one), gives nausea and radiates to the back. Heartburn can be a symptom of gallstones or it can be acid reflux or even peptic ulcer. To have a clear situation you should have abdominal ultrasound, soft tissues ultrasound of this lump, full blood work, liver tests (AST,ALT,GGTP), amylase, urine analysis. If no findings, upper GI endoscopy should be performed. Hope this will help. Regards.