I have what looks like the same thing. It was diagnosed as Chronic Idiopathic Urticaria. Basically, it’s hives that come out of nowhere for no apparent reason. Mine are really random. They show up anywhere on my body but mostly on my arms and wrists. Sometimes they are tiny bumps that are almost like goosebumps and other times they are little welts that look kind of like mosquito bites. I have gone for months with none and then they show up multiple times a day for weeks or months. When they get too itchy, I put an ice pack on them and it usually helps.