Does the 20 days of coverage for a skilled nursing facility restart if you return to the hospital for 3 or more days?

My mother had a 2-week hospital stay, went to a SNF for 10 days, returned to the hospital for 5 days due to critically low sodium level caused by a new medication given at the SNF, and now is back at SNF. Should her 20 days of coverage for the SNF restart after the 2nd hospital stay?