Hi and welcome to HCM To find a possible food related cause for the rashes, you will have to rule out each new item one by one. It could be any of the leafy veg or fruits you are using. Anything that you are not used to. Also make sure to wash everything well before using, to remove bugs, pesticides, dirt etc. TRy to start one item at a time and see if you develop the same reaction to anything in particular. Other ways of finding out,which may help can be to do allergy tests. But also note that allergies usually spread over the body, and are not usually localised to the chest alone. Try to recall any history of chemical/cosmetic exposure over the area, sun exposure, excessive sweating/oily skin/dandruff recently? maybe due to exercise? synthetic clothing. Any history of outdoor activities? pets/insect bites? similar complaints in family? Try to narrow down the cause and avoid it. For now apply a calamine lotion till it is healing and start an antihistamine daily for a few days to resolve any allergy. If you see no improvement in 4-5 days, do see a dermatologist to rule out non allergic causes. Also be sure not to over do the recommended amounts of leafy veg especially on a new diet, without proper dietician advice. Hope this helps.