I had something similar about 15 years ago. After a few months I figured out that the cause was a sensitivity to tannins and anthocyanins. Anthocyanins are the orange-to-purple pigments you find in the skins of fruit and vegetables (not beetroot, that's different, and not carotenoids as in carrots, oranges or tomato skins). Tannins (most commonly consumed in tea) are polymerized anthocyanins. It doesn't take very much red wine, tea or rowan jelly to set it off (also arthritis-like pains in my hips). It's not an allergic reaction, it takes a fair bit to set it off and none of the symptoms are obviously immunological.

Gotu kola seems to reduce the sensitivity - probably by thyroid stimulation, the enzymes that handle anthocyanins are thyroid-dependent.

Long shot that you've got the same, but cut back on tannins and anthocyanins for about two days and you'll know if it is.