You will find an in-depth analysis of the causes of such occurences in my book The Key to Health and Rejuvenation. There are certain foods that either bring this on or make it worse. These are the Pitta-increasing foods which have a heating effect to them when they are digested. I would suggest you go through that list and the explanations. Combined with the liver cleanses, the blushing will certainly subside. I used to blush just like that and also had such heat/sweat outbreaks, especially at meal times and during conversations (although I didn't have any confidence problems). It happens when the bile is secreted by the liver and relased by the gallbladder, but stones hinder its free movement, which causes excessive heat among Pitta body types. Once my liver was clean, I never blushed again.
With best wishes