I feel your pain, and worries. Once you have cancer, and go through the what you did, who wouldn't be anxious. You can always get a 2nd opinion to help ease your worries, and sounds like you are with a new ENT.

As far as the pain, try to avoid triggers or episodic events that cause it. Maybe you can get "break through" pain meds for when you can't avoid these triggers.
Some even get Botox injections for spasms.

You said pressing on the area helps relieve the pain. Maybe see about acupuncture, acupressure, myofascial therapy, physical therapy or manual lymph drainage.

I feel I have reduced blood flow from the racial neck dissection, and could be similar from your surgeries. I also have a bump under my chin, submental area, which I call a turkey neck, from the accumulation of lymphatic fluids that is common with neck dissections.

As far as Medicare, you can appeal any denials, and hope your issues are resolved.

I hope this helps, and good luck with the doctor.