When i laugh for longer than a minute or so i get very congested....?

i was at a movie over the weekend and i was laughing at this one part... and then from then on i couldnt stop caughing.. my lungs were full on gunk and i was very congested..and i dont have asthma..i already got tested for that..any ideas on what it might be? it happens all of the time.. even when im just with my friends and i start laughing.. i cant stop clearing my throat and then i get a headache.. but my chest isnt tight or anything.. just fluid-y