Help! Cluster Feeding Monster!

I'm a first time breastfeeding mom and my dear son is 12 days old. He was doing great and used to cluster feed at night from 1am-7am. The past 3 nights we had a routine down where he didn't cluster feed at all and just fed around every 3 hours. Starting yesterday and today he has transformed in to a cluster feeding monster ALL DAY LONG. Almost every hour, sometimes as little every half hour, he is wanting to feed and after a few hours I check to see if he is actually hungry and not just comfort sucking.

We have had no problems breastfeeding so far, good deep latches, feeds for about 20 mins, and he has had plenty of wet and soiled diapers so I know he is getting enough...

My nipple are starting to get sore and nothing is helping.

S.O.S. Please Send Advice!!