Sore and painful tummy tuck scar. Is this normal? (Photo)

Your scar looks like there is an opening it area of irritation. This can be due to irritation from deep sutures. I would reccomend following up with your surgeon to check the area and remove some suture material if present 

Based on your photos, it does appear the incision isn’t healing properly. This could be caused by a failure of some of the deeper sutures or the development of an infection. The scar should not be that red and swollen 3 months post-op, and the fact that you’re experiencing pain at the incision site is of great concern. This kind of complication could lead to dangerous infection and possibly the need for revision surgery, so schedule a follow-up with your plastic surgeon as soon as possible for proper treatment. Best of luck to you.  

This is best to be discussed with your plasticsurgeon directly. I would strongly urge you to speak with them and seek medical
attention as quickly as possible. Very best to you.

–Brian S. Coan MD, FACS

The sore part of your scar has not healed. You need to follow up with your surgeon and get it treated.