hello, your symptoms could be due to hormone oxytocin which causes uterine contraction leading to incision pain, which is nothing to worry about as this hormone is secreted upon brest feeding.
Usually three months is a sufficient time for incision to heal and for the scar to gain 80% of normal tensile strength of skin. You can take vitamin c tablets, once daily, or consume more vegetables and cutrous fruits like lemon, goosberry, orange etc to improve healing. keep the incision area​ clean, and mop dry after taking bath, do not wipe it. Avoid lifting heavy weights till it's healed. If there's pus formation, you should start with antibiotics to control infection and fasten healing.