I've been on welbutrin sr for 8 years. and it has been a miracle ...

I've been on welbutrin sr for 8 years. and it has been a miracle drug for me. I have bi-polar disorder, so am limited in terms of types of anti-depressants. Last week I went to have my prescription refilled, and the pharmacy told me it was back-ordered. They suggested I try welbutrin xl, same dosage, but once a day instead of twice a day. My doctor approved it, and I took it for 4 days. I couldn't leave the house, my anxiety was so bad. I couldn't stay awake in the afternoon, and couldn't sleep at night. I had a constant headache, and palpitations. I'm convinced that if I had remained on it, I was headed for a manic episode; the first in 8 years. So I called the drugstore, and they procured my old prescription for me. Anyone else have this kind of experience?