From what I have heard and read I would agree with API that it is a bacterial bloom. It shouldn't afect the fish much. Maybe do a water change.

I'm not sure...

. I wouldn't add the 7.5 proper again. With you adding it and the PH chnaging so quickly this could realy stress out the fish if it is changing more than 0.2 all the time. It is best to let them adjust to the PH you have. What is you PH straight out of the tap (without anything added to it)?
Sorry I couldn't help you more with the cloudy water.

I'd wait for Gunnie or Butterfly or someone more experienced to help you.
Sorry your having problems.
Gwenz
