It's more a Calcium issue than a pH issue. Like you know how mozzarella gets stretchy? And when it gets reeeeally stretchy it's soft? It's the same principle that's happening to the outer rind of your cheese right now. In mozz it's the breakdown of calcium. Here, it's the leaching of calcium into the water. You correct it by getting the calcium back into balance, which is 1 tablespoon 33% solution per gallon of water. To correct the pH, add a teaspoon of vinegar. Might need more vinegar, depends on your water.
You can also use whey instead of water to make up your brine. As a quickfix if you have no CaCl2, take some whey and add it to the brine. Boil if you think it's contaminated (usually not necessary for fresh brine)