Pea size lump on toddler leg

[Reenypip]

Was smoothing my 18 month old boy leg and felt a pea siza lump on front if his leg. Can't visually see it but can feel it.
Could this just be from falling over?

Bump

I will be taking him to GP if doesn't disappear next week.
You can't see it, but when smooth his legs firmly can feel if. Feels about a pea size and cartilage like (not soft not hard)

Best to see your gp. Cyst? Lipoma (harmless fatty deposit. - had a friend with one. Does it move?)

Very very slightly

When I touched it he did flinch and kick his leg away, but I don't know whether that just him telling me to get off rather than it hurt.

It's slightly to the side of the bone running down his left leg