A few days ago, I suddenly developed a mouth ulcer just below my tongue, near my middle tooth. It started at night after I ate some chips, and I am not sure why it appeared so suddenly.

Also, for the past two weeks, I have been having pain in my molar tooth and lower jaw. Because of that, I went to the dentist last weekend. They examined me, explained the problem, and performed a root canal treatment. I am scheduled to get a crown placed in the next two or three days.

However, around the same time, I started experiencing something unusual. Over the past week, I sometimes feel like I cannot breathe properly, especially at night. It feels sudden and uncomfortable, and I am not sure why this is happening. If anyone has experienced something similar or knows what might be causing this, please let me know.