Good Morning Zac,
Your ENT man will probably take a look but it would be a good idea to have a chat with your GP.
If the lump grew from nothing to the size of a pea overnight it is either one of the fastest growing cancers on record or something else and I would put my money on the second option.But don't ignore it, see your GP, no one can afford to take a risk where there is even the slightest chance of the growth being malignant.
Giving up smoking is a smart move, it is not easy, stick at it. Never ever again have a puff of a cig or cigar etc one more puff and you go back to square one. When you feel you need a smoke remember the worry you have at the moment and ask yourself "is it worth the risk?" and remember this; something like 85% of mouth cancer patients are smokers!