Yes, good advice Mike. Fortunately I just found and ordered some from a Thai online health store,
http://www.thaiorganiclife.com in case any other members in Thailand need it.
In fact though I think I might have jumped the gun on the HITH worry -- just took my first up close look since yesterday and I can't even find the little mark that was on his head. Besides a 30% water change yesterday after noticing the mark, I've fed him twice with fresh garlic juice soaked pellets. Not sure if that helped or not (could have also been the vitamin supplement I added after water change, or both), but again no mark now (and to note, there was never any kind of 'pimple' and his usual active/aggressive behavior and voracious appetite never changed).
I'll keep monitoring him of course, and as a preventive measure I'm still going to give him epsom salt soaked pellets for 2-3 days after that arrives.