I don't wish to interject an unwanted opinion, but what you have described here is a clear indication of post surgical infection. Please do not wait until morning to have it evaluated by a medical professional - I implore you to seek emergency help now. My thoughts and prayers accompany you and your husband.
get to a hospital NOW. this could become septic long before morning.
get in the car and get to a hospital NOW. do NOT wait. Please.
That sounds suspiciously like blood poisoning or phlebitis. Don’t wait. He should have had discharge papers with a list of things to report immediately should they occur.