Slow healing is commonplace everyone heals at a different rate radiation isn't like any other kind of burn, it not only does immediate damage but it has long lasting repercussions. I doubt at this point Hyperbaric dives are needed you are too close to the end of treatment still for it to seem like it is a real problem.

However, a few things you can do to help.

treat it like a wound. Ever cut your finger or scrap your knee? What do you do? Clean it bandage it and let it heal.

Same premise (without the bandage)
Anytime you take something by mouth. Clean (brush teeth - using a mild toothpaste - like a children's toothpaste even - cuz minty adult stuff BURNS and you really don't want to irritate something already irritated) and rinse. Keep that lovely baking soda mixture too and use it in between to clean, and rinse your mouth out (the mixture is actually healing too)
The idea is to keep it clean to facilitate healing.
next - up your protein (iron) - I'm a veg head so I use a protein power to ensure I get my daily supply of protein.

Why? well protein (converts into iron) iron binds with O2, which facilitates HEALING (this is what a HBO dive does but it does it on a much faster/larger scale) Not enough protein/iron - not enough O2 transportation - poor healing.

MOVE - okay I know you feel crappy and fatigued... but MOVE - walk the dog around the block even once or twice a day - and that will increase your circulation, increase your O2 intake and therefore support/promote healing - more 02 to bind to that iron, and it moves faster to the area - if your circulation increases... force yourself. I'm not saying run a marathon... just don't lay on the couch all day either...

finally PATIENCE...

I healed VERY quickly post treatment - now they say it takes one month for every week you've had of radiation - that puts you at 6-7 months to feel OKAY. Now as I said... I healed very quickly however - it's almost three years out since I had my surgery (feb 4), and three months shy of my having finished the three year mark for rads (may 4) and guess what? I still get improvements monthly. And to be honest - it's almost double the time frame they suggest to even touch feeling - GOOD.

hugs.