HELP!!! Why do i seem to be choking a lot lately?

for the past moth i've been choking on everything and i mean everything like i would be at the shops (this has actually happened) just walking, my mouth closed, breathing through my nose, not eating or drinking anything and i just started choking and anything i eat or drink i choke on i mean it's like that little flap thing thats meant to stop stuff from getting down my breathing tube isn't working... is there any reason for this and if so and cure???? please help