I get a burning sensation on the back of my neck after entering a sauna for a few minutes that's like a sunburn with no rash. started happening recent?

Don't use that sauna: Maybe where you are sitting in the sauna under a heat source. Anyway your skin is being damaged! That is not the purpose of a sauna. Listen to your body! Stop it!

Burning in neck: Did you have any injury recently or strain? is it right after spending hours at a computer? Could be you have strain or even mild disc dysfunction ( though you are quite young )and with the vasodilitation that occurs, it registers as pain/burn ( sometimes pain is burning. Could try massage before entering or one tylenol/ motrin and see if it makes a diffeernce f/u with doc