Pred does cause nervousness and hyperactivity. If you gave the pill this morning, I would not give one this evening and then call your vet in the morning.
The way we use the medication for skin is that you start at a high dose and then slowly bring it down over the course of a week or so. It will not hurt for the dog not to get the second dose tonight...make sure you call in the morning.
DR.V
Dr. D.A. Vamvakias
Veterinarian