It looks like toothbrush trauma as you said, nothing to worry. It will take some days to heal. Continue using warm salt water gargle or Chlorhexidine mouthwashes.
U can use antiseptic gels like Dentogel or Rexidine gel to ease healing.
Next Steps
Use softbristled toothbrushes Like Colgate sensitive or Oral B ultrathin sensitive toothbrush.
Health Tips
Direction of toothbrushing is gentle upward and downward motion.
Hope this helps.. Have a great weekend..