Radiation continues to work just as long as treatment lasted, 6 weeks, so things are still going on in there to kill the cancer. Healing takes longer, and everyone is different. Just continues maintaining your oral care, pain medications, adequate nutrition, and prescribed exercises, and it will come along, maybe not like before, but better than 4 weeks post treatment. I could not eat by mouth until 14 weeks. See you speech and swallow therapist about the trismus, which can interfere with oral care, eating, and speech, and may be more noticeable 3-6 months post treatment due to muscle fibrosis, so exercises everyday like you are doing have to be performed. They have adjustable gauges opening contraptions that can help with the mouth opening, but forget name.