Oh, I am sorry...but I think I would get a second opinion. Sounds to me like your vet may be overlooking something important.
I wouldn't wait...I have said this many times, but it bears repeating here, when dogs actually show signs of pain...it is intense for them.
I think I might even request an x-ray to be sure that nothing was left inside (although with a neutering, I can't imagine that being invasive enough to leave something...) It could be herniated...lots of things...but it is certain that something is wrong and I would not continue with a vet who is willing to "wait and see".
I wouldn't wait...I have said this many times, but it bears repeating here, when dogs actually show signs of pain...it is intense for them.
I think I might even request an x-ray to be sure that nothing was left inside (although with a neutering, I can't imagine that being invasive enough to leave something...) It could be herniated...lots of things...but it is certain that something is wrong and I would not continue with a vet who is willing to "wait and see".