I second that. Calcium citrate solubility is 0.085 g/100 mL, vs 74.5 g/100mL for calcium chloride. You want to restore the Ca2+ ion balance in the milk, that's why you're adding it in the first place, and the citrate just doesn't dissolve well enough into ionic solution. The carbonate will act as a buffer, so it's unusable as well.
Can you find some cacl2 on ebay and have it shipped internationally, then make your own 30% solution? That stuff lasts forever once in solution, but make sure you dehydrate the cacl2 for accurate measurement.