Please calm down, take it easy. 30 mg of 2C-B is very unlikely to cause any danger and numbness can be parasthesia which is an uncommon but not impossible effect that may belong to the tactile effects of this drug. The effect may be more enhanced because of changes in your blood circulation from the temperature difference of the bath. It can be a result of reduced blood flow from vasoconstriction. 2C-B is a relatively benign compound and if it is truly this drug that you took, comfort yourself that I'm not aware of any serious complications anyone had from this quite normal (albeit high for some) dose.
So if there is nothing else, relax.
A friend of mine had issues on 2C-I combined with other drugs and felt numb with loss of sense of cold and hot. His panic and psychological difficulties were prominent but there was no real reason to worry. Look, I'm sure that if no other symptoms present you should be fine. Of course I cannot be sure, but if I were you I would see if there are any other symptoms that ARE worrisome. You could report them here but also remember that despite help we want to offer we are not a diagnosis unit, we cannot give you real medical support. I just think you are overreacting at this point and don't need the medical support. If you do, you can always seek more urgent medical attention you cannot get from people around you.
Actually quite a bit of time has passed. I expect that you either acted on your panic and/or had more symptoms or calmed down a bit and numbness subsided. Which one is it?