Hi there. I also had a c section - 4 years ago - and I still get pain when I move - doing sit ups or pilates. I also have a large tender area under the scar on the right side where the wound drain was.
I think that if you have another operation your body grows collagen for the new scar, and all the old scars get a mild dose of it also. That might explain why your old scar has re-activated.
In my experience of scars and who scars the worst and takes longer to recover, those with dry thin (prone to wrinkles) skin get over scars very quickly, and those who have very young looking plump skin scar easily and have raised and keloid scars very easily - with the advantage that they age well.
I read in a cosmetic surgeons book that Scandinavian and fair skin (not oily) skin scar best (but age worst) with darker, olive coloured and black skin (and oily) skin have the worst scars (but best aging).
If it's very painful I would go to the GP, or ring the surgeon to get another appointment with her.
Pulling the scar and rolling it is very good to release adhesions - it's painful but gets elasticity into it. Stretching with arms up over your head when pulling in your tummy is also good to release adhesions. Move your body to left and right without twisting your torso, so you get a good stretch along the side of your body.
Good luck, and please let us know what your GP and surgeon recommend!!