Hi. are you hypertensive? If yes it might be Meniere's.
The head pressures, vertigo and bad taste in the mouth could be a part of pre migraine attack or aura.
Hello~It appears to me that your neck may have some pinched vertebrae, I highly suggest seeing a chiropractor. I know when my neck is not right, I have dizziness and other uncomfortable symptoms, but after an "adjustment" I am so much better. The chiropractor will take some x-rays of the cervical region, study them, and then go over the findings with you. After a few treatments you should start to feel better.
Also, yes, a B12 deficiency cause cause lots of symptoms, so adding the supplement should also help, also, the herb, Ginkgo is great for these symptoms as well. Try taking a good, high potency "B" complex, this will have all of them in the correct dosage as they all work synergetically.
I hope you feel better soon.