Pancreas. Many medications adversely affect the pancreas and cause pancreatitis. It is very serious and needs to be evaluated as you may need to stop treatment. I would go to the endocrinologist or gastroenterologist and have them check it out as soon as possible.
Everyone one with full cirrhosis, meaning cirrhosis with portal hypertension has splenomegaly (an enlarged spleen). Normally there is no issues caused by having an enlarge spleen besides a low platelet count and sometimes a low RBC count. Pain is rare in those with splenomegaly.
If a CT scan "showed nothing" than you don't have an enlarged spleen as it is obvious on any abdominal imaging study, ultrasound, CT and MRI and is always noted in the report. An enlarged spleen can also be detected easily with a physical exam similar to a liver exam where it can be measured and felt with the hands as a enlarged spleen is usually palpable and will extend down to at least the lower ribs.
Muscle pain doesn't show up on imaging so maybe it is related to that? Imaging only shows anatomical abnormalities which is not the cause of all pain.
Only a doctor can diagnose the problem. Please see your primary doctor as chest pain can be a sign of something serious.
Good luck.
Hector