Bump on baby’s head after ventouse

I had a ventouse delivery 2 weeks ago and my baby’s head had a bruise and a bump on his head where it was attached. The bruise went away in a couple of days, but the bump looks pretty much the same after 15 days.

I tried to do a little research on it, but I found the information available on it quite confusing; some people say it should only be there for a couple of hours while others say it may take months for it to go away. Has anyone had a similar experience and when did it start disappearing? Any tips on how to accelerate the process? Thank you!