Dehydration plus low blood sugar would be my bet. That was my problem once, same symptoms. It can be hard to test for, because low blood sugar (hypoglycemia) is usually only occurring at the time of the symptoms. In my case, my blood presdure would drop at the same time, & boom! Out like a light. They found my problem due to good timing, I had an episode while in the middle of having the test run. Mine was caused by anorexia nervosa, sounds like your bad diet caused the same problems. Get healthy, exercise, do some deep breathing. Anxiety goes along with all this, so meditation along with the deep breathing. Substitute V-8 for that damned Red Bull. I personally don't think the pot had anything to do with this, but now is not a good time to alter your mind in anyway. Wait untill you're healthy again.
~~~~~~~~~~~~~~~~~~~~~~~PEACE!~~~~~~~~~~~~~~~~~~~~~ ~

Of coarse hoards of other deficiencies & what Este said, & when blood sugar & blood preasure bottom out at the same time, you WILL hit the floor unconscious.