I doubt that you store enough of those recreational drug to feel any effect. Used recreational drugs in my late teens and early twenties, and even though I have changed the fat in storage many times since and have not felt flash backs. I think that you would have to do a lot of a certain drug to store enough to cause a high, from it's release, and release would be quite slow even if you were starving. An alternative explanation could be that the MCT oil kick started your ketone production, and you weren't used to burning them with full efficiency yet. The resulting levels of ketones in your blood would then be responsible for the sensations you had!

Fat cells store fat and trace fat soluble substances. They are not storehouses of the drugs we have taken.

I don't think those things are toxic... esp compared to the real toxic crap-- like trans fats and metals. Maybe those do affect one as the fat is burned.

Edited to add, if you are feeling that rough, then yeah I think something is wrong but I don't think it is simply detoxing from stored toxins. There must be some other factor at play.