Just a note: Since Calcium citrate powder (1 lb.) from Frontier Naturals isn't to my knowledge available at that store, but is on Amazon.com, and it unwise to delay treatment, I would get a source of calcium carbonate powder if available from Vitamin shop, and if not then a tablet that you need to pulverize to powder. A bit more to do to get the measure for the divided dose including pulverized the tablet and divided it with a one edged razor blade or flat edged knife. Look for the elemental amount noted in mg. on the label, as the other amount listed is just for the weight of the tablet.
Ordering the Calcium citrate is still worth doing, for if this issue is caused from MBD then your squirrel will need support of it for some time to come. Don't forget the magnesium.
Should you not have a set of the mini Teaspoons to support using the above measure for C. citrate, they available on Amazon.com.
This is the link to those mini teaspoons, that make using the C. citrate very easy to do. This vender has free one day shipping with Prime.
https://www.amazon.com/Norpro-Stainl.../dp/B0009X1P9S