My dog keeps chewing his tail

[Gingefringe]

My very boisterous 2 year old cocker has recently started to chew the end of his tail. At first he was chasing his tail but now he's nibbling the end. Yesterday it was bleeding - I only noticed because the kitchen units were splattered with blood from when he was wagging his tail!! Is it serious enough to warrant a visit to the vet incase it's become infected or is this something he's likely to stop doing?
He also loves eating any kind of poo but that's another matter .....