Thank you for your query on Healthcare Magic.
The bump is due to a scalp hematoma
which developed after the fall 2 months ago.
Nothing to worry as it is not causing any discomfort to the child and it usually spontaneously resolve gradually.
In next well baby visit you can show the lump to Pediatrician
and get examined.
Soft spot (anterior fontanel ) will fuse by the 18 months of age so still there is time to close.
Hope I have answered your query.