I am sorry to hear you are worried about Alfie. My name is Rebecca. I am a veterinarian and will do my best to help.
However, since he is young and the lump is not painful, it is proba There is no way to know what any lump is, just by looking at it and feeling it. It could be a "foreign body", a thorn or something that got under his skin and the body is making a wall around it. It could be a blocked saliva duct. Cancer in a dog this young is rare, but possible.
The best way to tell what any lump is would be to do FNA, fine needle aspiration. This is not really invasive, does not usually bother the dog at all. We take a small sharp hollow needle and poke into the lump (most dogs let us do this with no sedation or restraint, and it takes only a few seconds), and then look at what what was obtained from inside the lump under a microscope. This will usually tell us if this is an infection, a blocked saliva gland, a benign cyst, etc. and then knowing what it is will tell us the best treatment. Treatment might even be just leaving it alone, but you need to know what it is first.
Does this make sense? Let me know if this is helpful and what other questions you have.