My new baby ornate croaks and has a big bubbly neck...

[Socrates]

I wouldn't worry about the inflated neck. When my White's tree frog croaks his neck will remain slightly stretched out for a few minutes following his loud calls.

[Greg M]

This seems pretty normal. You clearly have a male, and they often sit there ready to croak, partially inflated. My ornate croaks whenever the spirit moves him (which happens a lot) and is almost always got his throat partially inflated...

You didn't mention length, but my guy is about the same age and is more or less full-grown at a little over 4 inches S-V.