Can overstim happen because of the cold? Because I walk to school in the dark and the lights and noise of the street always hurts but it's always so much worse in the winter and the cold because of the way cold temperatures feel on my face. Also, can overstim come in the form of a really intense headache? Because I get a weird feeling behind my ears and there's a lot of pressure behind my eyes and it all just feels really bad but I can't tell if it's overstim or just a headache.
Cold can definitely cause overstimulation, as can heat depending on the person. For many of us, sensory overload feels like a weird headache and pressure much like your describing, often along with everything seeming more intense (lights seeming brighter, sounds seeming louder, etc).