Since treating my own eczema was one of the reasons that got me studying Chinese medicine and as I had it as a baby, I’ll offer my favourite formula up as well. DGSNT could be a potential. I used to noticeablely sweat less than most of my Kung Fu students, but this last few months after regular dosing of DGSNT, I’ve definitely sweated a lot more than normal and my skin is better than normal. And it was one of the formulas that helped my eczema the most. Even though I have a big left guan, the hollowness of it can still point to DG potentially. Also reacting to heat and cold like you mentioned makes me think of Arnaud’s description of Jueyin, and hence DGSNT treats JYin.