What can i do to stop this?

I'm hoping it's just anxiety, but at least once a week I suddenly get "stuck" in the middle of a swallow of liquid, or I feel a belch come up and I actually get FOAM come into my mouth. I can't breathe during these episodes and my windpipe locks down for about 10-20 seconds. I gasp and wheeze and feel like I'm going to die. Then it relaxes and returns to normal. ... But these episodes are very scary. I'm a 14 year old male. HELP!