First, get yourself a test kit. Don't rely on others to tell you what your pool chemistry is.

Second, what product did you use to "shock"? Granular or bleach? And if granular, what was the ingredients (cal hypo, di-chlor, tri-chlor)?

If you have contaminants in the water, that will use up chlorine very quickly, and your pool will not hold chlorine for long.

It would help us if you would post all the relevant water chemistry numbers:
FC, TC, CC, T/A, CA, pH. We would be better able to help you.

CaryB