When I'm cold, I itch all over when I do hot exercise, and my skin looks like I've been bitten by a million ants.

Heat rash: mental stress, or a slight increase in body temperature after exercise. The heated blood flow stimulates the thermoregulatory center of the brain, excites cholinergic nerves and releases acetylcholine. If the skin is allergic to this chemical, an allergic reaction will occur. Because of wearing more clothes in winter and poor ventilation, it is more prone to symptoms of heat rash.

Most patients lack vitamin B/C, eat more fresh fruits and vegetables rich in vitamins or take vitamin C and B groups, or B 6 in group B.

Eat more alkaline foods, such as grapes, green tea, kelp, tomatoes, sesame seeds, cucumbers, carrots, bananas, apples, oranges, radishes, mung beans and nuts.

Usually take a bath or clean the affected area with warm water, and avoid scalding with hot water, so as not to aggravate the condition. 999 dermatitis flat ointment should be used externally, and vitamins C and B and honeysuckle dew should be taken orally.

It will take some time to cure, because it is related to your own physique (many allergies are acquired), so you should improve your physique spontaneously, eat more vegetables and drink more water at ordinary times. Auxiliary catering and medication.

I hope my answer can help you and I wish you a speedy recovery!