lump on the gum

[buzzles]

Posted in NL but probably better in here. My 2 yo has a strange, dark red, marble sized lump on his gum. Not sore to touch but does bleed if poked. Any ideas on what it could be- haematoma, bot fly, abcess? Here pic, not great quality though

 

[the watcher]

Looks like an abscess or infected tooth, I would call the vet, it might need anti b's or removing