I have an intensely itchy rash to one side of my face that is spreading quickly to my jawline and neck. it's happened before but i can't figure it out

DERMATITIS: Did you use any new cream or lotion ? It can be contact dermatitis or allergy to something you applied on that face. Pls see md to DX the problem. Herpes zostet has pain and vesicular rash.

Hives?: If the rash is spreading rapdily within hours, it is possibly hives, see an allergist, especially if it happened before. If the rash is spreading over days, it could be a contact allergy and I have seen such rashes as a reaction to plastic cellphone cases, if you hold the phone against your cheek. An allergist can help you figure it out.