DCIS and possible recurrence within mastectomy scar

Original dx extensive DCIS, stage 0, 10/98. Had right breast mastectomy with TRAM Flap reconstruction. No chemo, radiation or tamoxifen. Age at original dx 36 yrs/ 52 yrs old now. Aggressive cancer type Comedo form, several lymph nodes removed and all were negative of cancer. Annual checkups NED / clean so far.

This past September, I woke up one day to a feeling of soreness within my mastectomy breast scar. The scar is relatively thin except for a small area that is thicker and a tad bit raised. I know it sounds odd but I could not even tell you if it was always that way or not. This past summer my original breast specialist retired and I had made an appointment to see a new breast specialist. She did a (hand type) breast exam over the summer and she said all felt good and she would see me in a year. Upon feeling the soreness in September I went back to the doctors office and the doctors oncology nurse did another breast check. She said all seemed fine with no feeling of any lumps. She then gave me a script for an ultrasound for my piece of mind and sent me on my way. I had the U/S shortly after with no findings. The radiologist even came into the exam room and scanned the breast herself..mentioning the thickness as nothing abnormal and said she does not see any recurrent disease. Here we are two months later and I am still aware and feel that sensation. Should I contact the doctor again and request an MRI and/or biopsy? Do you think a clear U/S is enough to let this go? I have read numerous posts about the recurrence of DCIS even after mastectomy and am now very worried. Any advice on my situation would be appreciated.