Confusing OGTT results

I have been a "fainter" most of my life. It has become more persistent recently, so the doctor has ordered several tests in attempt to pinpoint the cause. One of my triggers to fainting spells is when I haven't eaten so I took an oral glucose tolerance test. My fasting glucose level was in the normal range (95). In hours 1-2 my levels went into the pre-diabetic range and stayed there until hour 4 when it dropped sharply to 60. My A1C is normal. I am 24 years old and a healthy weight, I eat healthy and exercise regularly. What would cause both the high and low sugars? If it were prediabetes wouldn't the levels stay in the high range? I also had other blood work done and my B12 was low; this might be irrelevant but I thought I'd throw it in just in case.

Fainting symptoms:
dizziness
lightheaded
loss of vision
nausea
cold sweating with clammy skin
shaking
numbness/tingling in extremities

other symptoms:
headaches often
inflammatory bowel
nausea often, especially after eating

[teenagediabetic]

Its really does sound like diabetes in which the symptoms relate to hypoglycemic episode ( low blood sugar ) if you have the tests done and they do not say you have diabetes I'm really unsure . Hope thingd get better for yourself xxx