Anytime you shock the well, you can expect a bunch of crud to come loose which could partially clog the injector. A clogged injector reduces the pump's ability to build good pressure. You may need to clean it out more than once.
That however would not account for sucking air. Chlorine will attack metal and so if there is any metal pipe or hose clamps in the well, they could have been compromised. Assuming no top side checkvalve, if there is a suction side leak, it should become a pressure leak when the pump shuts off. I say should, because it is possible for a leak under suction tonot leak under pressure.
Push down a poly pipe alongside the existing suction line and put a Tee at the top of it, leaving the bottom open. Put an air valve and a pressure gauge on the Tee and pump air into it. The pressure it reads will tell you where the top of the water is at the time.