Is there any other symptoms like fever??
Any history of insect bite??
It's mostly inflammatory swelling
Need to examined first for surrounding area condition and if any similar swellings over the body
If pus point is clearly visible..better Drain by just needle prick in aseptic conditions by Surgeon
In the picture pus point not clearly visible if present or not
Next Steps
As it's being for a month better go for blood counts and put appropriate antibiotics
Consult paediatrician and then General Surgeon
Health Tips
As of now try to soothen baby by paracetamol syrup with dose 15mg/kg body weight 4times a day
Avoid contact at swelling.
Have gd hygiene for baby clothes like Dettol,hot water after cleaning them