I'm a bit behind here, but wanted to let you know we're thinking of you.
Sorry to hear that yesterday was kind of rough. Ouch!
Meanwhile, I wanted to mention a brand of mouthwash that I'd heard about several weeks ago, when I was reading up on chemo side effects, since I knew my Mom would need chemo. A common chemo side effect is mouth sores, and several women on a breast cancer forum mentioned Biotene mouthwash in a thread that was for 'chemo newbies' - a shopping list of sorts to help be prepared for chemo side effects.
I bought two bottles and took them with me to visit Mom, unsure as to whether it would be available in her area.
In any case, a few days after her first chemo, her mouth got really sore. I woke up one morning and Mom had been up half the night with various side effects that started to kick in, but she said, "That Biotene mouthwash you brought me saved me last night..."
I wonder if it might help you? You can find it in regular grocery stores, drugstores and so on. I paid about $9 a bottle for it here in the US, and up in Canada it was more like $15 or so. It's marketed as a remedy for dry mouth, but on a breast cancer forum, the women there writing about how to manage chemo side effects (including sore mouth and mouth sores) raved about Biotene's ability to help prevent mouth sores and/or treat and soothe them.
Mom said it was excellent and greatly alleviated the sore mouth she was experiencing.
Hope this helps a wee bit!
editing to add: I realize you're not doing chemo, but as soon as you mentioned possible mouth sores, I wanted to mention the Biotene in case it might help you out too.