Thank you for sharing your question and photographs. I would recommend seeing your plastic surgeon for an in-person examination. It is difficult to offer definite advice as this may be due to skin thinning, loss of underlying fat, scar tissue formation, or development of skin laxity. Through feeling of the tissues a diagnosis can be made and treatment recommended. Hope this helps.
If you had liposuction or weight changes after lipo of the area, it could be related to that. Hard to say without an exam.