It is caused due to release of histamine and histamine like products in the blood .The causes are infections, medications, bee
, food allergies, environmental allergies, stress, cold temperatures etc. Sometimes the causes are idiopathic. The symptoms of STDs include warts, ulcers, yellow or white vaginal/penile discharge, burning with urination, pelvic pain, bleeding between periods, testicular pain and joint pain etc. You do not seem to have any of these symptoms.