My Husband Has Been On Oxycontin And Percoset For 5

My husband has been on oxycontin and percoset for 5 years due to a brain cyst. In order to undergo surgery for a pressure test and a crainial port at Johns hopkins in Baltimore he was told to discontinue all opiates. He has been off opiates for 3 weeks however he went off them completely in 6 days. he seems to have been through the worst of the symptoms however he is experiencing severe bloating. His stomach is extended and hard. He is exremely depressed and in a lot of pain. His dr believes this is due to the opiate withdrawl. is this normal after 3 weeks?