The scar appears inflamed and almost a keloid. It can be injected with a steroid which will alleviate the itching. The injection may need to be repeated a few tines.
A cyst has a small pore that communicates with the outside. Usually that pore is removed along with the cyst. It sounds like that may not have been done in your case.
You should have your surgeon check it out. It might be normal swelling but it could also be fluid or blood accumulation which would need to be addressed.