This was one of my earliest symptoms - one February!
I knew there was no chance it was real sunburn, in England, in Feb.
Went to doc, described it exactly as sunburn. Was concerned it might be the start of a thrombois, as we have it in the family.
Caught her on an off day: she was not impressed with what she obviously thought was timewasting & paranoia on my part.
I did get an apology, when I eventually got diagnosed, because she said: “Oh yes, you came in with that thing with your leg, didn’t you?”
Anyway, as to what to do about it, I don’t believe there’s any point applying stuff to the skin, because it isn’t really sore. It’s an illusion caused by your brain or spinal cord being sore!
Some types of prescription neuropathic (nerve) painkillers may help.