What Causes Recurring Redness And Burning Sensation On Face?

I have a question about my face turning red. For several months, for no reason, a certain place on my face turns red and then it feels like my face us on fire. It starts out about the size of a quarter and then spreads all over my face and stays that way all day. I ve tried to see what triggers it but can t figure it out. I m not stressed, haven t eaten anything, no new make up, etc. I ve checked my blood pressure and blood sugar both and they are normal. It gets so bad that it almost turns purple and is hot to the touch. No other place on my body does this. Any ideas?