I Have Accidentally Discovered That Hot Water Releases An Allergic/itch

I have accidentally discovered that hot water releases an allergic/itch reaction in my skin when it is irritated. This started once years ago when I had poison ivy and accidentally contacted hot water, either in a shower or at the kitchen sink. I learned that running hot water over the irritated skin released a reaction that feels like a sneeze in the skin. It is very intense at first, almost orgasmic. When I have an irritated itchy area and release the itch in this way, (in my mind, I am releasing histamine, I don't know if this is true), the skin no longer itches for a while. The hotter the water, the better the release. As long as I don't burn myself, am I hurting anything by doing this? These days, I do it when I have swelling from lipo-lymphedema, usually in the summer. Hot weather makes my legs swell and itch. I will run hot water in the shower, release the itch, then finish with a cool rinse and soap and water. I apply grape seed oil after drying off, which a lymphedema nurse online once recommended for itch and which does really help. But the hot water when showering makes the itch release immediately and go away for a while. Is it releasing histamine or something else in the skin? Is this hot water release of itchiness generally known? It works best if I use the spray as if I were scratching with it, moving it over the skin, up and down, back and forth. Hot, hot water. Do allergists know about this?