There is no wY to tell you what the lump might be or how to treat it. Is it on top of the skin or under the skin? Is it hard or soft? It could be some infection, a bite, an abscess or even Puppy Strangles,which can be fatal.
If you are concerned, the best thing you can do is have your Vet check it. That way, you will definitely know what it is and if it needs treatment.
It is sorda hard but it is movable is that okay? And it just appeared out of no where.
I can't say any lump, especially on a puppy that young, is ok.
You really should have a Vet take a look at it.