Going by the sites involved in your case, seems like only the sun exposed sites are involved....ie face, upper back, chest and arms....So incase you feel that you have any kind of irritation or itching that develops on exposure to sun , then you might be suffering from photodermatitis or sun sensitivity..
Photdermatitis may result in swelling, a burning sensation, a red itchy rash
and sometimes even peeling of the skin. There may also be blotches where the itching may persist for long periods of time. The rash in this case is seen mostly over the sun exposed areas...
Prevention includes avoiding exposure to the sun and wearing sun block on the affected area.
Cover up: wear long sleeves
Wear sunscreen at least factor 26 with a high UVA protection level
Other than the general precautions as listed above , you might need to take antihistamines(antiallergic drugs) for the initial acute episode atleast along with topical steroids
,,,so if there is no improvement with the general precautions , then visit a dermatologist
so that your condition can be assessed and managed accordingly////
Hope it helps
Dr Geetika Paul