I dont think the lump feels squishy, like it has fluid in it... When it happened last summer I thought it might be an abcessed tooth too... but I poked all around Dockers mouth and he never flinched once... it doesnt seem to bother him at all.
As for his eating habits... Im not sure... Steve free feeds so its hard to gauge how much Docker eats.. it doesnt seem to affect his eating though...