Infection a month after vasectomy

[coopie]

Hi my husband has his vasectomy on 28th November 09 his recovery had
been great until yesterday when he came home from work with a fever,
feeling sick and a pain in his lower back which travelled around to
his front. He then told me that a few days earlier he had noticed
that his right testicle had swollen. We went to the out of hours
surgery where he received some antibotics and iburofen, (I read on an
earlier article that if taken together the iburofen is less
effective!) Never knew that! He also told him that it may need to be
drained! Anyway he was told to go and see his own gp which he did
today where she changed his antibotics to stronger ones given strong
pain killers and was meant to leave a urine sample, but unfortunately
he was unable to do this as I think he was dehydrated after the fever
and now with New Year the surgery is closed until Monday! So hopefully
the antibotics will start working or he has been instructed by the doc
to head to A&E if still in pain. He is finding it hard to walk and is
in extreme pain.

What I can't understand is why antibotics are not given after surgery
to stop anything like this happening and I don't understand why it
took 4 weeks for this to happen? Anyone have any advice?