It is indeed unusual to have the symptoms you are having. I suspect since you just came off the Master-Cleanse your electolytes may be off kilter and you could have an imbalance of electrolytes. First of all, drink some fluids. Diluted apple juice with a pinch of Sea Salt and a tsp of Sugar or honey or maple syrup would be good.
Is there any chance that you have Emergen C packets??? It is an electrolyte replacement with mineral ascorbates and vitamin C. If you have vitamin C I would take some. Especially if it is sodium or calcium ascorbate. Take a couple thousand milligrams or 2 grams or so.
Is there someone there with you? Try to make sure someone is there with you in case you faint again. I would feel better if you had someone there to help steady you as you walk or just keep an eye on you.
If you don't feel safe to stay at home go to the hospital and get checked out.