We have found today a lump on our boy and are very worried. It is at the base of his
p---s.(sorry not sure if can use word)It is quite large but swelling comes and goes but he flinches when you touch it. He is on antibiotics for a skin infection and needs to see vet about that tomorrow but looking for any advice worried sick! He seems fine other wise. He is 15months old.

Is it about halfway between his penis and his testicles? If so it's most likely the bulb of his penis - the part that swells when a dog is aroused, and causes the tie when they mate.
:)

thanks jeang we are a bit niave to doggie bits . but that sounds right thanks tonight we have noticed it has gone down feel a little silly now.

Please, don't feel silly! Anything that seems unusual can be a real worry. The only silly question is one you ask when you already know the answer.
:)

thanks again . Haven`t posted since he was a puppy as hubby has had operation on his back and is off work over a year. We were going to show him but obviously things have not worked out as planned. He keeps husband company when Im at work. He does make us laugh at the funny things he does.thanks again for your help.