We need to know your cya reading. How high you need to shock is dependent on your cya reading. Without it, we are only guessing.

Another big issue is your low ph. Seems like you overshot your target when adding acid to lower it. Since 6.8 is the lowest reading on your kit, your ph actually could be much lower. Add a half box of Borax slowly to the skimmer while the pump is running. Wait while to let it circulate and then retest and redose to get to 7.4. Once it starts moving up, you'll probably need smaller doses or you'll overshoot it.

We also need a alk reading. With the way your ph is bouncing all over, I suspect it is probably low.

Repost with cya and alk readings. Run your pump 24/7.