Also if you can massage inside your mouth and along your gums with your clean fingertips.
Place your thumb and forefinger on either side of the gum and massage, gently in circular motions,and move along the gum repeating this as you go.
Spend as long as you can doing this.Maybe at bedtime when you are winding down,ready for sleep.

The gums are like a muscle which can retract when tense causing them to recede from the teeth.(This can happen after having some dental work ,probably from the trauma)

By doing this gentle massage you can help to relax it back down again.

Also first thing that comes to mind for gum problems is to take plenty Vitamin C.