Hi Jason. I'm not sure I can help but I've got some questions and curiosities. They may help others help you.
What kind of meditation practice do you do? After you stop practicing, how long does the anxiety/experience last? Do you experience anything like this outside of your practices? For how long have you been meditating?
Maybe it's some kind of energy blockage that you are needing to work through. I have experienced discomfort and fear in meditation. This usually comes from overdoing practices/pranayama. It is a fear not easily describable for me - I recall the sense of a vague awfully large scale and a hollow, awful dis-ease. Some might recommend that you simply be still and aware of what you are experiencing - but I find depending on the nature of the experience; it can be a sign that too much is going on internally. Although regardless, what you are experiencing doesn't sound like something I'd want to willingly sit through. Perhaps you are very sensitive to practices.
I went through periods where because of sensitivity I couldn't manage to meditate for longer than 5 minutes or I would experience negative symptoms - so I just shortened my meditation to a point where I was comfortable - which often times was only a few minutes. Over time blockages dissolve away.