Don't think it's a mucocele, but...

I have this hard lump in my bottom lip.  And when I say 'in my bottom lip', I mean just that - it's not on the inside of my lip, but in the fleshy, put-lipstick-on, what-touches-other-lips-when-you-kiss lip.  Whatever it is is pretty deep inside the lip, too - there's no discoloration, just a part of my lip that's swollen and painful if I, say, try to bite at it.  (More painful than just biting at another part of my lip.)  I'm not insanely worried about it, because this lump has come and gone before - always in the same spot.  I don't really remember how long it's lasted in the past.  It doesn't seem to match any of the descriptions or symptoms of mucoceles that I've found online - mainly because it's not on the inside of my mouth, it's deep inside the lip itself.

Any assistance in determining if this is just a special snowflake mucocele that doesn't want to be normal or if it's something else would be greatly appreciated!