Dr. Hanif warmly Welcomes you!
Thanks for consulting at my virtual clinic. I have carefully worked through your case, and I can realize your health worries. Being your physician, I assure you not to worry as I will take care all of your medical concerns. 
If baby isn't ill looking and mood is normal and he is playing and there is no 
vomiting or 
nausea, and baby is eating and drinking properly then there is nothing to worry about. If he is wetting his diapers normally, he is alright.
This is just a 
hematoma formed due to direct physical impact on the scalp and accumulation of fluid on site of 
injury. Apply ice spongings and just observe the baby. He will be alright. You may give Infant 
Tylenol 2.5ml for the pain and swelling.
Hope it helps. If you need further, detailed and quick assistance related to any health issues in future, feel free to 'ask me a question' directly from my profile.
Have a wonderful time ahead. 
Best Regards!
DR. MUHAMMAD M. HANIF
USA