Most dancong doesn't have a heavy roast; usually a high amount of oxidation and a traditional, but not heavy, roast.
Could be just too much hot qi (whether in the tea or something else). Pomelo, cold qi tea, or other cooling stuff might help. Eating things like mango, lots of spicy food, etc. may do the opposite.
If you use toothpaste with sodium laurel (or laureth) sulfate, try switching to an SLS free brand.
Skilfaut... wrote:What I would do is try to rule out any effect of chemicals (as in pesticides)
Yeah I think that may be good idea. Some teas that I find questionable will give my tounge a sensation that it is on the borderline of developing an ulcer or bump. This has always been with tea that was 'sketchy' or from places that I just don't really trust very much. I stop before it happens and wash my mouth with some good tea
So far I have only had this sensation with a fake dayuling, a 'high mountain' sun moon lake oolong, and a cheap green taiwanese tgy. Also I noted a strange effect these had on my heart. I would get a noticeable increase in pulse and a slight feeling of unease. I would not attribute this to caffeine even though to some that may sound like its effect.