Have you seen a physician? There are no doctors on here. What you describe sounds like a blood sugar problem, but only tests by a doctor will get you started on how to fix this. You first need to know what's going on. I would ask, have you seen doctors about this? Have you been diagnosed with chronic low blood pressure or is this something you have self-diagnosed? If self-diagnosed, why are you constantly checking your blood pressure? These are just questions, but again, if you truly are having such large blood sugar fluctuations and blood pressure problems you need medical help. It's impossible to come up with a program to fix something if you don't know what it is you're trying to fix.
Hello~This sounds like weak adrenal glands or Addison's disease. Sometimes after prolonged periods of stress, our adrenal glands can get weak, this can in turn cause unstable blood sugar and low blood pressure. I highly suggest seeing your physician, he/she can do the required blood work and any other tests that are necessary and then can prescribe a good course of action for you.
The best option would be to see your Primary Doctor Paxiled. Low blood pressure doesn't necessarily mean anything is wrong. Some people are simply prone to low blood pressure, just as others are to high blood pressure.
When was your last physical? Last bloodwork?
The shaking after eating sweets may be related to insulin sensitivity or insulin resistance. Adding a lot of carbohydrates in your diet when you don't normally consume then can cause a fast rise in glucose levels and a quick drop, which might be behind the shaking.