Thanks for writing your query.
Swelling in eye can occur after forehead injury
due to soft tissue
swelling. It usually takes few days to weeks for the swelling of the eye to subside.
Itchy feeling can occur when the scar starts to heal.
I hope your doctor must have adviced you anti inflammatory medicines. these will help in reducing the pain and swelling.
If you are noticing any furthur problem, you should contact your surgeon.
I hope this is helpful to you.