Hi Dave,
I am unable to comment on the shoulder pain, however,
I will tell you that about the only thing my husband will eat on a regular basis are foods loaded with sugar.
He currently lives on doughnuts!!! Candy bars any type of surgar filled junk food. On a nutruitional basis I would not exactly recommend this diet, however, he is eating an putting a little weight on. He also at this time had no evidence of cancer.
Hope that helps with your sugar question.
I pray your mom's pain can be managed.