Tell us what formula you got exactly. Pet stores usually recommend the wrong stuff.
We can help you dose your baby but we need info from you.
We need the baby's weight. A scale that weighs in grams can be purchased at Walmart inexpensively - in kitchenwares. YOU will need a 1ml or smaller syringe without the needle. We will need to know the size of the prednisone pills in milligrams.
The sooner meds begin the better the chances for the baby.
You also need to read this:
https://www.henryspets.com/1-baby-squirrel-care-guide/