Lump Between Legs What Is This Lump Between My New 7 Week Old Kittens Legs?

What is this lump between my new 7 week old kittens legs? - lump between legs

Before you say something is happening to the vet, but I want to know what to expect

which really is not between the legs, but just before the legs through the stomach, worms, or think that it is only something that can disappear, but you can tell me what could it be?
THANKS