Maybe their is trauma from your tooth. Warm saline water rinses two to three times a day, and wait for a week, if it heals then okay, if it doesn't heal then consult doctor online or offline for better guidance and treatment options. Maybe you need to correct any sharp edges on your tooth, as they are more declined toward your tongue, causing trauma to tongue.

Hello Looks like the teeth are placed more towards tongue and it's constant trauma ....Don't worry just go and show ur dentist .

Its absolutely normal you have some  lymph nodes at posterior part of tongue. Which might have got inflamed because of systemic reason.