I Think The Weed Supply is Being sprayed with bad chemicals . I have been smoking for decades and NEVER heard of this effect before. It is not lack of oxygen because cannabis brings more oxygen to body parts. I really believe that they are poisoning the plant, in the field or during drying. Look what they doing at McDonalds on Youtube you wont believe it.
Hey there! This has happened to me several times. Like 10-12. The way you describe it and feel it coming on is very scary! These have ranged for me from lesser experiences, to more severe. Sometimes on the lesser severe I have been able to get some cool air, a cold drink or lay back on a bed or floor and control my breathing to avoid totally passing out or even complete loss of sight. This evening however, WOW. I have not smoked in a while and was visiting some friends. We smoked a couple bowls of good weed. I was very high and the head-rush and clues came. I warned my friends, then within like 20 seconds lost complete vision as it slowly blurred out. They told me my eyes were open but I completely lost coherency. I went totally pale and they say I was breathing, then seemed to stop. They laid me on my back and were ready to start CPR while another friend called 911. I came to while she was on with 911. We cancelled the emergency. This was extremely scary! That's the reason looked this up tonight. Today was my 53rd birthday and these 10 or 12 times started when I was a newbie, 13 or 14 years old, This was only the second time I actually past out completely. The last episode I had was like yours where my legs gave out and I had to lay down or fall down. These suck. I call it weed induced epilepsy. I wonder if blood pressure or something more. I have no major medical issues that I'm aware of like blood pressure or diabetes. I will be scheduling a physical now. Hope this helped!