I am currently withdrawing from Lexapro myself. I have the brain zaps and feel dizzy. I have gone through several SSRI withdrawals so I am used to it. Your symptoms sound totally normal. Once your body stabilizes on the 15mg, the sensations should subside. I was on 20mg for a while and then dropped to 10 mg for about 8 months. I told my doctor I just wanted to go cold turkey at 10 mg since I would feel just as bad when decreasing the dose by tapering. Please note, this notes for me and I am not suggesting you do that. Anyway, give it a few weeks.
-Adam
This is normal for some. I was very sensitive. I felt weird everytime I dropped my dose down for a few days. Hang in there.