DIEP flap stomach hardness. Is this part of the healing process? (Photo)

I had a successful double mastectomy & DIEP flap surgery on March 10, 2017; however, I am having an issue. I just started my period & I am in physical therapy for one of my arms. The PT also massages my stomach scar to manipulate the fascia tissue. The area below my new belly button & under the scar downward is so tough, hard & sore!!! It is also extended. I am worried bec of the pain (5 or 6/10 on a pain scale). I would feel better if this was part of the healing process. Thank you!