My guinea pig has a lump on its throat.?

'My guinea pig has a lump on its throat. At first we noticed he had wonky, overgrown teeth, so we trimmed then, but now i've noticed this lump. It is roughly the size of a ping-pong ball and is on the side of his throat he wasn't using to eat. I think it is an abscess as it is slightly squishy and warmer than the rest of him. Is it life threatening?? and is there anything i can do as i would rather treat him myself than take him to the vets?