what options are there in relation to getting dental work done?!

I have never had any problems going to the dentist. i have had the same dentist my whole life and I have had pretty much everything done (fillings/refillings/extractions/root canals). Now for the past couple of years I cannot sit in the chair for longer than a couple minutes before I start panicking. i do not know what Im panicking about....nothing about the procedures and or tools bother me at all. Problem is I have to get wok done but I cant sit there longer than at most 3 minutes before I have to get up and leave. Does anyone know what the hell to do. My dentist says he has never seen this before....which has to be a lie as he has been a dentist for about 35yrs. Do i go get knocked out to get work done?