I'm suffocating, help!

Hello everyone,

I've been following lessons here for a couple of weeks and I love it! I assume all of you have gone through the same thing, so here's my question:

When I've used all my air on blow notes, I get a feeling of suffocation and I MUST breath in (also through the nose). Does anyone have tips as to how to overcome this and to learn to inhale gently and only through the mouth?

Thanks.