I had my first in person therapy session with a new therapist on Wednesday and it was good at the time- in that I was so nervous but I feel like there's potential for it to go well. 

I've felt so horrendously anxious since however to the point where I have no idea where this has come from and how to control it. 
Normally I feel anxious regarding my health, or overwhelmed about crowds and social interactions or specific things, but I feel like I'm genuinely going crazy right now. My digestive system is going crazy and although I'm worrying about that I just feel a general sense of panic and dread and like something terrible is going to happen/I'm going to die. I can't sleep and don't want to do any of the plans I have over the next few days, and have no idea how to calm myself down. I've been trying to relax, tried listening to music, distracting myself etc but nothing seems to be working and my mind is going 100× from one thought to another.

Is this normal? It feels way too of an extreme reaction for what was basically an introductory session where we touched on lots of my past breifly and didn't spend too long on anything really. I really feel like I'm overreacting but don't understand why I feel like this when I thought I was doing better Monday and Tuesday.
I'm worried about coping if I feel like this after every session as I have no idea how long this feeling will last and how I'm going to deal with it.
Any advice would be really appreciated.