what helps me most during an attack is air

I don't care if it's from a fan, a window, an open door, air really helps with my breathing

also nice soothing music helps me too (I tend to go for something along the lines of dolphin/ wale songs)

holding on to a comfort item if possible

getting away as far from the situation as you can (which I apreciate might be a bit difficult, given what you said above)