You could have heat-induced urticaria (prickly rash), or you could have food sensitivities toward additives in pork ribs, pork and/or pumpkins.  If you keep a food diary, eat each of these foods separately, and see if your symptoms are reproduced.  You may also consider having food allergy or food sensitivity testing done by a trained health care professional.  Vitamin C, quercetin and nettles tend to decrease this type of allergic response.

Karen J. Benton, Naturopathic Physician