Yes, I do take all the B vitamins, not just B3, and also I take a full range of aminos as well, so I know it couldn't be that..
Interestingly, I finally got the results of my thyroid back yesterday, and it's really good.. was really surprised.. I suspect by intuition, it is the result of taking the B3, and perhaps, yes, in the beginning, it did create a temporary imbalance state, while going from ying to yang.