Well if the vet is only about the feeding (which is why I asked) no need to take him, because honestly depending on the vet and it's hand on experience on snakes (specifically BP) you could be looking at anything from vet visit cost to tell you it's normal to blood test, x-ray, anti-biotic just in case which of course would not be necessary.
It is frustrating not to have them eat but at this size 6 month to a year would not be a surprise to me.
What you can do is give him time, make sure our husbandry is optimal and be patient.