Lump near dogs front Paw

[RK3280]

Hi,

I have an 8 year old German Shepherd.
About 2 weeks ago I noticed a bump near his front paw(not on it , but just beside it) and it is not bleeding.

He is limping on his foot, and it hurt him when I touch the bump.
He is eating fine and still likes to goes on walks and still plays by himself.

I decided to trim the hair on the bump(there was no hair loss) to get a closer look and it seems there is black skin there( as if something poked him and the skin grew back). I'm not sure if something may have gotten stuck in there and it is just swelling, or maybe if its a tumor.
I have posted some pictures, feedback would be very appreciated!

Thanks!