Hi. Thanks for posting your concern at HCM I would keep a possibility of urticaria/hives. I would definitely advice that you visit a dermatologist for a proper assessment of the rash. Urticaria OR hives can occur due to various causes like(to name a few) infections(bacterial , viral, fungal), drugs, certain foods, cold temperature, in response to strong emotions, exercise, pressure (prolonged standing, sitting), in autoimmune disorders like SLE, RA etc. A few cases have no underlying cause and are known as idiopathic urticaria. I would advice you to get few basic lab tests like Hemogram, stool for ova/cyst, Urine routine, Chest Xray. An oral antihistamine like Fexofenadine OR Loratadine once or twice daily for a week would be suitable. They are non-sedating and wont affect your alertness level. take care regards