How do I know if my internal sutures are torn?

Dear krossler1207,I understand your concern. However, without a proper assessment it would be difficult to determine what is wrong. It is best that you visit your plastic surgeon for further assessment. Only after thorough examination you can get proper recommendations and advice.
Daniel Barrett, MD 
Certified, American Board of Plastic Surgery 
Member, American Society of Plastic Surgery 
Member, American Society of Aesthetic Plastic Surgery

Dear K,    Front and side view pictures would have been helpful. The type of exercise recommendation that you received is quite unusual , however, it is unlikely that you tore your muscles repair, because 6 weeks after surgery the healing scar is very strong.   Most likely, you pulled a muscle, because you did too much while your muscles are out of shape. I recommend to my patients that they may return to the gym after 6 weeks, but do only 25% of whatever they did before surgery, the following week 50% and after two weeks back to normal.   In any event, since you are concerned, call the office and ask to be seen by your surgeon. With all due respect to the nurse, she did not perform the surgery and you will be reassured by being examined by your surgeon.           All the best,                           Dr Widder

When returning to exercise it is very normal to feel sore. At six weeks post op you are still healing but it is generally safe to begin resuming more strenuous activity. If you are too sore rest the area. It's best when returning to activity to do so gradually to allow the body to build back up to your previous level.

Generally speaking, it is difficult to "tear" a well performed abdominal wall plication.  If this does occur, it is usually associated with significant discomfort, swelling, and/or bruising. 

 I would be concerned, given your description of coughing and pain with deep breathing, then you may be experiencing a pulmonary complication;  best to let your plastic surgeon know of your situation/concerns.

 Best wishes.