I Have Choking/coughing/sneezing Spells Daily. They Can Last From A

I have choking/coughing/sneezing spells daily. They can last from a few seconds to a few minutes. They occur sometimes once or twice a day. but sometimes are much more often. I have been tested for allergies, acid reflux, asthma, etc. and all tests are negative. These "attacks' occur at any time; there seems to be no correlation to what I am doing at the time. This has been happening for a few years, and I don't know what to do.