Not sure if I have an allergy to garlic

I have always loved garlic my whole life but as I get older I seem to have a growing intolerance to it. Often I wake in the middle of the night with what feels like garlic coming back up on me and this produces a very fowl smell that no amount of brushing my teeth or gum chewing will help. I find it is very difficult to sleep when this happens and when it lasts through some of the next day, I feel very self-conscious about being near anyone. I am aware that most people have an odour after eating garlic but this is a great deal more than usual and very bothersome given it prevents proper sleep. Sometimes I think onions are doing the same thing. Has anyone out there experienced this and is it considered a garlic allergy?