Hi. i woke up with a rash on my neck that looks kind of like a hickey but more red.. i put tea tree oil on it and it burns a little. what could it be?

Immune system: Hi, Your immune system's reactions are directly reflected onto your skin as a rash. The most likely triggers are from a topical allergy (cream you use), food allergy (usually gluten/dairy), infection (yeast, etc), heavy metal, chemical or mold. Consult with me to get to the bottom of it. Hope this helps!

See a dermatologist: Forget the tea tree oil. It will not help, may irritate. Maybe it is just a pinch or a "hickey". Allergy is unlikely.