reading your symptoms it most probably appears to be a kind of urticaria
triggered by heat. urticaria is a common skin allergy
problem which is often associated with rhinitis
or asthma . its known as atopy. the reasons for urticaria are many and some times it can be due to food allergies or cold or hot season or even exercise can trigger the attack of urticaria. hope you have got your answer. homeopathy
has very good medicines for urticaria you can try taking homeopathy for the said condition.