advise large lump on mastiff dogs back ankle please help

[Doggylove13]

My dog has had a lump on his back ankle on the inside for 2 months it seems to be stiff and he was showing signs of pain when it was first noticed but now not showing so many signs of pain but lump has got a tiny bit bigger since it first appeared can anyone please advise what they think this is as I am unable to take him to the vets at the moment
He is only 2 years old and is a mastiff breed

 

[JudyN]

It's potentially dangerous to ask people online to say what it is from a photo - it might look just the same as what someone else's dog had which was harmless, but turn out to be something really nasty. Could anyone take him to the vet for you? Or you could send the photos to your vet and ask for their opinion. Some vets are more prepared to do home visits now - even if just in your front garden.