I've been on a lower dose of Wellbutrin XL in combination with Zo...

I've been on a lower dose of Wellbutrin XL in combination with Zoloft. Stopped taking Zoloft and upped my dose of WB to 300mg and then to 450mg. I felt good w/no side effects on the 300mg. I'm not sure if it was the WB, but after a couple weeks at 450mg, my head started to feel really weird. Not dizzy, not a headache, just feeling like I need to shake my head to clear it. I dropped back to 300mg and it's been a few days, but I've still got the weird feeling. Can't really focus. Anyone else have this feeling?? I don't know how to describe it other than maybe a head full of cotton balls.