Female dog in season?

Iv recently got another dog, a staffy! we rescued him from someone who wasnt taken care of him propely. Anyway we had him castrated the other day as my female german shepherd who is 5 years old came into season. Two days after the neutering he is now trying to mate with her, and wines alot, he also does this weird thing with his mouth when sniffing her lol is there any thing i can do or buy to help minimize the humping?