2 year old son lip injury - lump in lip

Hello,
9 weeks ago my son fell at nursery. We think his teeth went through just below his lip resuting in a "through and through".
Our local A and E referred us to another hosipital's MaxFax unit which we will told to visit the next day. The doctors were pretty helpful and they were prepared to stitch the wound but advised this would have to be done under a general anaesthetic as my son was so little. We looked at the would and decided that 1) it looked as though the wound was already closing and 2) we didn't want him to have to undergo a general anaesthetic. In addition as the injury was beneath the lip the scar wouldn't be that visable.
9 weeks on there is a very red scar. I try and put scar serum or bio-oil on it at night whilst he is asleep, but overall you don't see the scar as the lip "overhang" covers it. I understand that the redness should reduce with time.
But what I have also seen is when he smiles/talks there is lump in his lip. This is really bothering me...I am also wondering if it is affecting his speech a little. Is this scar tissue, will it go? Is there anything I can do for it? I am hoping that as he is so little that this should sort itself out.
I could add some pictures to show you and then you could see the bump when he is smiling but can't do this - would this help with your answer?
Many thanks for your help.