Sore gums can be common in pregnancy cause your baby it taking nutrition from you. Tell your OB/Midwife but also call your dentists. They might be able to give you tips and will probable check you for an infection.
Also try swishing coconut oil for 10-20 min a day and rinse with warm water. It eases gum pain and helps you heal. It's grainy when you start but warms up. Try working yourself from 1tsp up to a whole tablespoon full at a time.