Do you have to count social security payment as income that you now have to pay back?

If you pay it back in the same year you received it, no.

The taxable amount of benefits shown on your Form 1099-SSA will be automatically adjusted to account for repayments.

If you will pay it back in a later year, yes.

See page 15 of Publication 915 to see how to deal with repayments that exceed your benefits:

http://www.irs.gov/pub/irs-pdf/p915.pdf