Well done on opening up and sharing what you are going through, sounds like a extremely stressful time for you.
You've made a great decision booking in a teleconference with your oral surgeon, it is always helpful to get a bit of re-assure or piece of mind when our bodies are going through unusual pains.
Sounds like you have been through some really tough events recently, which have resulted in a lot of stress. Our bodies always respond in peculiar ways to stress, for some it might be extreme bloating, whilst for others it is tingling sensations in particular places.
I think it would be really helpful if you could set up a teleconference with a psychologist or counsellor. They will do their best to help with your stress, and might be able to give you some insight on your burning mouth if the oral surgeon cannot. It also might be worth looking into calming exercises to do when your mouth begins to cause pain. You could trial out exercises like deep breathing or EFT tapping.
I think it's great that you suggested your son go on some outside walks, do you join him? It might be a great way for not only you to enjoy some fresh air yourself, but just to have someone to speak with - you can ask him to tell you about the video games he likes, or if you feel comfortable, talk about the stress you have been under.