Cobra neck from loose skin & no fat in center, 35 years old, 8 months post-op neck lift (Photos)

Thank you for your question.
If all the photos submitted are post-operative, the contours suggest volume excess from the digastric muscles and lower part of the submandibular glands.
Although the initial tension can camouflage the problem, as the skin relaxes the differences in volume between the central part and the lateral part (under the jawline) become obvious.
In general, adding volume under the chin can improve the smoothness but that the expense of losing the benefits of previous surgery.
A deep plane neck lift can address the remaining volume by reducing the digastric muscle bulk and plicating them in the midline as well as reducing the lower part of the submandibular glands.
Additional skin tightening may be possible but may also not be needed

We do this frequently in our office and call it a cobra lift, we do skin removal, muscle tightening (platysmaplasty), VASER and J Plasma all to contour the chin/neck in one treatment. Best, Dr. Emer.

It's hard to give a formal answer without a proper physical examination. Liposuction addresses the superficial fat. The contour in your neck is composed of more than that. You have good skin quality in the photos. The deep neck anatomy consists of you intedigastric fat, digastric muscles and submandibular glands. That is what is in between the boarders of your jawline. I think that doing the liposuction revealed that interdigastric muscle fat and accentuated it. My opinion is to address the deep neck anatomy. A surgeon that can guide you and provide a comprehensive approach to cater to your specific needs is mom advice. I wish you luck on your search! 

While your surgeon thinks it may be loose skin, it looks like residual submandibular glands which have become prominent after the liposuction and platymaplasty. Taking out more skin may accentuate the problem. Gland removal during face and neck lift surgery is done by a few surgeons and is not usually part of the routine of corsette platysmaplasty, unless the subplatysmal contents are explored after lifting the platysma. It's best to look for another opinion.