you haven't mentioned whether these red patches are associated with any symptoms such as scaling or itching,or are increasing in size nevertheless with your description it likely seems to be an allergic reaction
to irritants such as nickel as in jewellery,shellfish,animal dander,pollen or exposure to extreme heat or cold
these patches could be prevented if you can identify the allergen and keep him away from it.application of calamine
lotion could give some relief.
it would be better if u consult a dermatologist
near by to rule out other causes of the problem