Swelling or muscle repair failure? (Photos)

I'm sorry to hear about the concerns you have after tummy tuck surgery.  As you likely know, your plastic surgeon will be your best resource for precise diagnosis...
Generally speaking, abdominal wall "swelling" after tummy tuck may be related to:
1. Swelling in the soft tissues. This may take several months to resolve and may worsen with increased activity or at the end of the day. Patience is required to allow for resolution of the swelling. 2. Fluid accumulation in the space between the skin and the abdominal wall muscle. this may consist of blood ( hematoma) or serum (seroma). This fluid accumulation can generally be diagnosed by physical examination ( occasionally ultrasound may be helpful). Treatment consists of aspiration; several episodes of aspiration may be necessary. 
3. Separation of the abdominal wall muscle repair may lead to a swelling/bulge appearance.  One of the steps of a tummy tuck procedure involves reapproximation (plication) of the rectus muscles. These muscles have spread apart during pregnancy and/or weight gain. Bringing them together again in the midline helps to “tighten” the abdominal wall as well as to narrow the waistline. Your photographs are not concerning to me when it comes to the possibility of abdominal wall muscle separation.
  
4. Residual adipose tissue may be confused for swelling. Again this is most easily diagnosed by physical examination. Additional liposuction surgery maybe necessary to improve the results of surgery.
Generally, it takes many months for swelling to resolve after tummy tuck surgery and it may take up to one year (or greater) a complete skin redraping to occur.
 Best wishes. 

Thank you for your question and photos. You should expect to have swelling for three to six months following tummy tuck surgery. Use of a properly fitted compression garment will help decrease the length and severity of the post-operative swelling. As the swelling decreases, the contour of your abdomen, flanks, and hips will dramatically improve. Please follow your plastic surgeons specific advice regarding your level of physical activity. Hope this helps and good luck with your recovery.

It's best to talk with your board certified plastic surgeon about this. It is possible to break sutures after surgery. It is also very early in your recovery process and there is still swelling. It is very normal for the tissues to relax during your recovery process - they will never be as tight as they were right after surgery. Congratulations on your surgery!