My Husband Is Currently Taking Oxycodone For Pain That Is

My Husband is currently taking Oxycodone for pain that is not going away in his abdomen Hip and left testical , he is taking 10mg tablets and he gets a burning sensation in his stomach is this normal? He also has high Liver emyzime levels and Hep c that is currently being treated although he is not on meds for it at the moment. He is in remission from Follecular Lymphoma Cancer. TIA