Ask a Pediatrician Online and Get an Answer ASAP
Hello & welcome to Just Answer! If you have any questions after reading my answer, be sure to let me know.
This is possibly a small hematoma (blood collection)
if there is increasing size of swelling or redness, or tenderness, or pus like discharge, this would require review from your pediatrician,
otherwise just wait and watch over the weekend, and this may improve spontaneously,
Do leave a positive feedback if this information is useful,