"Shock" is a state and not a chemical or product. When you add chlorine to suddenly raise your CL ppm (the amount of chlorine in your water) you are "shocking" your pool.
Can you post all your test results like PH, CYA, TA, FC and CC? Also, are you experiencing any issues with the pool water such as cloudiness or green coloration?
More info will surely help get you back on track.