Hi @sapphire1158. I would (and have) trusted the Mayo staff with my life. If they feel they got all the cancer out then that is really good news for you to only be left with surgical recovery. Not everyone gets radiation, chemo, or both in addition to surgery. Sometimes no surgery but chemo and/or radiation is the solution.
The PET scans in my experience often show scar tissue which is indistinguishable to the shadow of cancer. It is expected to see the scar on the scan and it apparently establishes a baseline for follow-up scan(s). I am not a doctor but have addressed this issue time and again not only with my own scans but with many others as well. When PET scans a performed a few weeks or even three months out after surgery, it should be expected to see scar tissue. A keen doctor or diagnostic radiologist can tell the difference between cancer and scar image. If they question an image results they may ask for another scan in three or six months looking for change in the image.
The dry mouth, the taste buds messed up, this is part of it as you heal from the surgery. Radiation messes with that for years but it seems surgery alone isn't as hard on the taste senses. The salivary glands may have been bruised or damaged as a result of surgery. That might take a while to resolve. You may want to record your thoughts about that for follow-up appointments with your doctor(s). Some like myself have had salivary duct(s) rerouted as we healed. In my case my nose runs when I eat, twenty-two years now. A friend of mine had a duct leach out from the side of her neck just below the left mandible. She will place a napkin there when she eats. Most however recover nicely without issue.
This is all scary stuff. It is all out of the normal of life, surreal if you will. Courage. It's a life changer this cancer stuff. But for most as well it is put behind us with a new appreciation for life itself. Good healing.