I think you said you had HTH Super Shock and Swim #3.

If so, that's Cal-Hypo and with your calcium level you shouldn't use it. If it was Di-Chlor it would be, in this situation, a good choice. So would Tri-chlor pucks but not those "double-acting" ones laden with copper.

So you'll need to get some CYA/Stabilizer powder. You can use the Muriatic acid to lower your pH for now. I'd start with 1/4 to 1/2 cup--no more. Mix it into a 5 gallon bucket of pool water first, then add it. Safer that way.