You might try rinsing and gargling with salt water, or rinse regularly with Listerine with a little peroxide added. If nothing like this helps, see a physician or dentist. If it from biting your cheek (either by accident or habit), rinsing should help heal it. Again, if it persists, consult with a professional. You could have something more serious.
You may need to put your finger over your teeth to keep your damaged tissue away from your teeth when you chew for a couple of days. Do this when you brush your teeth.
I find putting a little hydrogen peroxide on the wound helps heal it. But not reinjuring it is key, and chewing and brushing teeth are when I tend to hurt it the most.
The tenderness may be from a swollen lymph node.
The ulcer on your cheek is likely to have been caused by you biting on it whilst chewing food.
You can purchase Bonjela from the pharmacy or from a large supermarket to apply to the ulcer. This will protect it from being aggravated by your teeth.
The sore jaw is likely to be from a virus, or wisdom tooth coming through it they haven't done so.
Best wishes.