Thanks for asking the query,
According to your clinical history i suspect that your child is showing the symptoms of teething
, due to erruption of decidous teeth exerts pressure on the gum pads leading to swelling & poor oral hygiene
, further adds up to the condition, so i would advise you to maintain a good oral hygiene of your child.
Use lukewarm saline and antiseptic mouthwash rinses.
If the symptoms persists or worsen i would suggest you to visit a Pedodontist and get a checkup done.
Hope this helps out.