I am an RN and the taper sounds fine, you should not be having any withdrawal. Based on my experience, I have a few questions. What is your baseline blood pressure and have you been drinking lots of fluids? If so has it been water other fluids? Usually if I don't drink enough I get a headache easily. Also feeling lightheaded or dizzy when you stand up is a sign of orthostatic hypotension. What that means (if you are not familiar with it) is that your blood pressure drops some when you stand up and the dizziness is a symptom that you feel if it drops enough to feel it.
Back in December I had an episode of feeling "off" and this January I just had surgery and had another episode of feeling "off" and almost passed out. I didn't even feel dizzy I just felt different than normal. My blood sugar was fine and by the time I was able to check my blood pressure it was a low normal. Long story short after talking with primary MD, ENT, and seeing a cardiologist for the first time ever, having a head car scan, 2 EKGs, orthostatic blood pressures, and an echo cardiogram, the cardiologist thinks it was related to dehydration. Because my blood pressure is normally on the low end of normal if it drops, I don't have much of a reserve, therefore I feel symptomatic. His solution add salt to my diet to bring up my BP, how ironic!
by all means though don't brush it off. Talk to your doctor!