What is wrong with my neck? Platysmal bands? (Photo)

Yes those are platysma bands. Since they are  more pronounced upon animation and not at rest, I would recommend you to get botox injected to the area.  

It would be best to consult with a board-certified surgeon in-person as you may have more than one option. The presence of banding down the front of the #neck, and, amount of excess skin and condition of your skin are among some factors which determine if you are a #candidate for #rejuvenating the neck. Chin deficiency with the neck and jawline are also taken into consideration. A weak #chin implies a lack of chin support for the skin along the neck line. As a stand-alone procedure, chin augmentation can be performed in the office under local #anesthesia. For individuals with signs of aging in the neck, a chin implant added to one of the recommended procedures above, will provide optimal results.
Patients who desire facial rejuvenation that is affordable, quick, and effective should also consider the Lite-lift™. Like the Life-Style™ facelift, this is a modified facelift, individualized for each patient, that can be performed in the office with a local anesthetic and improve signs of aging around the neck, jawbone and lower face. These procedures are not "Thread-lifts" or "String-lifts". We do not use the "barbed" sutures employed in these other lifting operations. The Lite-lift™ uses longer lasting techniques that are discussed below. Because the incisions are limited, there is less bruising, swelling and healing time for most patients. Many patients can be back to work in one to two weeks looking rested and more youthful.A board certified plastic surgeon should evaluate both your anatomical features and aesthetic goals to suggest which procedure best suits your needs. In some cases there may be more than one option to choose from. If you are not a candidate at the time of your #consultation, your board surgeon can recommend non-surgical alternatives to address your concern. 

Neck bands can be improved with botox and deep RF heating such as thermage or sublative.  I have had success with smart lipo even just for tightening if there is some laxity.  If you want a more permanent improvement, thermi or platysmaplasty are the way to go.  I suggest a noninvasive approach at your age, and see a cosmetic dermatologist with experience in neck rejuvenation.

Yes, your presence of Significant (Platysmal) Banding is what is bothering you– this requires bringing the muscles together in the upper/mid neck to a more youthful position and occasionally their release. This procedure is called a platysmaplasty or platysma plication. Mild banding can be treated non- surgically with Botox or Dysport but this requires injections 3-4 times a year for maintenance

They are the vertical platysma bands that are visible because you are skinny at your neck and maybe due also to the early aging. They have correction with a properly done neck lift in experienced hands, a muscular lift, but I deem it is too soon for you for such major procedure. Give it a think.