I have had vertigo since being in University. I get it on and off every once and a while. If your husband is getting worse, he can try these exercises. Literally you lie on a bed and move your head to different positions, slowly and hold it there for a few seconds.
Make sure you are in the room with him. The first time I did them I nearly passed out, but they fix me up fairly quickly, occassionally I have to do it twice.
They fix the problem in about 80% of the cases and I have no idea why more doctors don't try them first. The first time I had vertigo I was given medication that literally made me sleep 18 out of 24 hours.
Clearly, I am not a doctor, so make of this what you will, but read over the symtpoms, see if they fit. I use the Epley maneuver, listed under the office procedures and I have always done it on my own with doctor.