My mother recently underwent surgery to remove her left kidney due to a malignant tumor. The other kidney appeared to be free of tumors. her surgeon assured us the cancer was localized and that all would be fine. It has been slightly more than a month and mom appears to be recovering, however she is plagued with nausea. some days the nausea is so bad she can not eat. She gets dry heaves or vomits bile. Other days she vomits all the food she has eaten. Could this be related to her other kidney? Her doctor thinks it is a reaction to her pain medication. she has been on 25m of fentanyl patch for several months. and it doesn't seem to be letting up.