Honestly I would say that it could not be the pot, until this last month. Nothing has ever happened to me like this, or anyone I knew until recently.

But in the last month, this has happened to two different people I know. Albeit, they fell and hit their heads. They were smoking blunts, I blamed it on nicotine poisoning from the wrap. That can't be your problem.

I'd say what it is is this. And this is a complete guess, please understand this.

You just took a few big huge rips, your lungs ache a bit, and you aren't breathing your best. You might of coughed in a hearty way for a while after the rips. You overexert yourself with limited o2 supply going up and down the stairs, it affects your eyesight, and you pass out from that.

If that isn't even close to something that sounds likely, then the only other explanations are: Sudden allergic reaction to marijuana. Not unheard of, not likely either, or your bud was laced. No one laces bud. Lacing costs a lot of money. LACING COSTS A LOT OF MONEY. dealers don't waste money.

All the help I can give you friend.