Not a doctor, but obviously our body is NOT happy about something. Your BP is telling you that. Since you have no dysautonmia diagnosis here is the poor mans tilt table test. NOTE- only do this if you feel comfortable doing it. If you have a BP cuff or pulse ox it makes it easier, but if not you can do this by just taking your pulse. Sit or lay down in a resting position for 10 minutes or so. Long enough for you to feel like our body has acclimated and has calmed down. Take your heart rate (and BP if you can). Now, stand up and immediately take your heart rate (and BP) again. If your heart rate goes up more than 30 beats per minute there’s a problem. It’s called POTS. You can keep standing if you want and take a few more readings to see what your BP and heart rate does but honestly you probably aren’t going to feel good from the sounds of what our have already written.
As for the trouble chewing and tongue numbness, depending on if it’s the front of our tongue or back of our tongue certain cranial nerves are probably being compromised. The 9th cranial nerve is responsible for the gag reflex and the back 1/3 of the tongue. The 7th cranial nerve controls the front 2/3rds of the tongue, salivary glands, and other functions. http://en.wikipedia.org/wiki/Cranial_nerve Nerves can be compromised for lots of reasons but in our situations intercranial hypertension is a good first guess. The 9th cranial nerve is buried deep in the brain and is supposed to be hard to injure.
Anyway, the poor mans tilt table is a good place to start. Here is more info on POTS. http://www.dinet.org/pots_an_overview.htm