If it is an allergic reaction, at least you have narrowed down the foliage and can either avoid that plant or, as RickCorey suggested, see if other varieties of tomatoes cause the same reaction. You may need to get an allergy test done, and specifically include tomato foliage as one of the tests (you may also be sensitive to other things you are not aware of). I've occasionally had bouts of phyto-photo-dermatitis (rash caused by certain plants reacting to sunlight). My dermotologist was able to immediately diagnose the condition, but advised me it would be next to impossible to figure out precisely which plant was causing it. More likely to be in the umbelliferae family, which covers a wide range of both cultivated plants and weeds. I usually chase the shade when gardening, and have doubled down on that strategy both for that specific skin rash and also to avoid skin cancers which run in my family. Good luck and I guess stay away from your lovely tomato plants unless fully protected.
