Hi.
A sensitivity culture by the vet followed by a course of the most suitable anti-biotics based on the result. Though they usually prescribe some broad spectrum anti-biotics immediately while they wait for the results to come back.
if he thinks it might be caused by an underlying problem there may be more tests - but until he sees the snake he won't know if any of those are needed.
He will also likely ask if there have been any regurges or strange body positions lately and if this is a new snake or if you have added any new snakes to your collection lately.
dr del