I'm 5 years in and still learning. I spent at least 6 months thinking it was claustrophobia. Or work stress. Or hypersensitivity to lightning (weird, I know, but as a child he survived a lightning strike and I thought that the electrical sensations he felt were from a storm coming in.) He does things that actually tell me he has an anxiety attack brewing before he even knows it--he clears his throat a lot. He wiggles his nose strangely. He gets a weird grimace on his face. I don't understand what it feels like for him, but I can warn him so he takes his medication.