What can I do to get relief from canker sores that arecaused, perhaps, from mouth trauma?

Try OTC. Topical preparations (like benzocaine) can help with pain . Try rinsing with a mouthwash 3-4/day. This might be painful, but often helps the ulcers heal up faster. If the ulcers are not healing or are happening repeatedly check with your md.
Baking soda. A solution of one teaspoon baking soda in one pint of tap water used as rinse 4 times per day will help sooth. Avoiding spicy or very hot foods or liquids if possible will help also usually.
Diagnosis of pain. The history is very important for treatment options. Has this patient had oral herpes before? Is the pain gettiing worse? Is there any difficulty swallowing? Locally the patient can do mouthwash with saline. A culture may be indicated to define the virus. In severe cases an antiviral medication may be taken. Popsicles, ice cold liquids, and drinking chilled aloe vera gel may help pain.
Topical treatment. Triamcinolone which is a steroid and available in a topical form can be prescribe in an ointment called orabase can be applied three to four times a day and will relieve pain and aid healing.