did you take a benadryl? It does sound like some sort of reaction.
I would be very careful from now on when coloring hair.
From what I understand, a severe life-threatening analyphylactic reaction occurs shortly after exposure. You've about 5 hours since exposure so I wouldn't be too concerned at this point. Continue with the benadryl and hopefully all will be clear in the morning.
In the future, however, I'd be very careful about exposing yourself to hair coloring products.