 [ Symptoms ] the skin on my upper arms is red like sunburn but it is permanent i am very fair skinned not blond or blue eyed i stay out of the sun indoors as much as possible but i am often asked if i have been laying out in the sun i do use sunscreen if i am going to be outside even in the shade when i exercise and get overheated the skin will get a darker red and feels hot to the touch i cannot find any information about this problem and i try to hide my arms if i can i cannot stand warm weather and get overheated easily so i do not like to wear long sleeves [ Disease ] maybe lymph nodes enlarge or become tender in response to an infection or inflammation in their immediate drainage neighborhood since your doctor was not able to find a source for this pain or inflammation it would not be inappropriate to have some basic tests first like a cbc   complete blood count many things including dental disorders can cause an enlarged lymph node so consider a visit to your dentist as well