I am 30 years old. i have a girlfriend and stepson and of course our two year old dog rusty. he just got nutared and found out he had heart worm. my dog rusty got a parvo shot on top of that and now has a lump as big as a golf ball on his neck. the vet keeps saying its normal and it will go away but it hasnt its got worse im very worried and need to find out what to do