Violent "hiccups"/Diaphragm spasms

Has anyone with stage IV stomach cancer experienced what I would call violent hiccups/diaphragm spasms that occur every time you shift positions (roll over in bed, sit up, stand up, or eat/drink)? My husband had these for several weeks after his first two rounds of chemo where they gave him C/D/F and has them again (only worse) after two rounds of I/L/F. The doctors say they have not seen this and said they could prescribe a muscle relaxant. If anyone has had this, can you let us know and also, what can we do to stop them? Thanks.