I had the swelling under the chin. Lots of it, especially with radiation. Sleep very elevated at night. I used a reading pillow for awhile, to help the fluid drain during the night and not get any worse. I did not have therapy, I just rubbed gently horizontally and vertically every day and eventually the fluid will find a way out. I had a neck dissection and jaw surgery.
hope this will help a litte. Hang in there