Hello,
I cannot confirm anything without examination but it sounds like solar urticaria.
It is the development of hives minutes after exposure to the sun, which resolve in less than 1 hour.
Apply a good sunscreen with minimum spf 30 atleast half an hour before going out in the sun.You can take non-sedating antihistamines such as Cetirizine or Loratadine(Claritin) when the rash appears. Short courses of oral cortisone or steroids are taken for short periods (one to three days) to settle more severe symptoms.You may take Vitamin C along with the prescribed treatment. Vitamin C is a general anti-allergy supplement. Also apply calamine lotion and a mild steroid cream like dermacort on the rash.If the symptoms persist then pls consult an allergist.
I sincerely hope that helps.Take care and pls do keep me posted on how you are doing or if you have any additional doubts.Kind regards.
I recently had a similar symptom. I am fairly dark complected/tan easily. Have spent some time in the sun and tanning beds my whole life (Im 23 years old). I havent been in a tanning bed in quite some time, but recently went. The next day I noticed red/purplish spots all over the inside of my forearms (rang in size of tiny-small freckles). I have had a few similar looking spots on the tops of my hands before after tanning that later turn darker brown, than lighter brown, then the disappear. This is also happening with the spots on my forearms. They went from red/purplish, to dark purple, to dark brown, and now they look like they are fading (currently light brown). I am assuming they will disappear as the ones on the tops of my hands have in the past. However, I have never had such a severe case and was wondering if anyone knew what this was or if there is any treatment.