OK, one more idea to add to this list of good ideas. Your description of being hot, panicky, and sweating describes me perfectly when my thyroid comes "on-line" and I warm up. I'm not used to my thyroid feeling stimulated, with its interplay with the adrenals. Your mention of it being connected to vitamin C made me think about Dr. Abraham saying vitamin C helps improve the cellular transport of iodine. Made me wonder if the iodine is now getting into your body better. Also, vitamin C supports adrenal function, which might respond erratically at first to an increase in dose. Pick and choose if anything applies. Best wishes!
Abraham, G.E., Brownstein, D.,Evidence that the administration of Vitamin C improves a defective cellular transport mechanism for iodine: A case report. The Original Internist, 12(3):125-130, 2005 http://www.optimox.com/pics/Iodine/IOD-11/IOD_11.htm