It sounds like you know what to do
Hello,
You mentioned either calling your doctor tomorrow, or getting checked out at the hospital tonight.. it sounds like you are being safe and sensible and I would encourage you to take care of yourself by consulting with a doc just like you posted.
As for the panic attacks, if that is what you are experiencing, IMO, our brains are so used to having our "substance or drug of choice" we actually feel very scared or panicked to be missing them from our systems.
In my experience, I just do some deep breathing techniques in order to calm down... and I also have tried to eliminate as much stress as possible, at least for these early months of recovery. And this works for me.