Although C.J. Williams has been unable to run for more than a week because of a fever and a series of headaches, the Shrewsbury High senior is upbeat about the season and the challenges ahead. “I came down with a pretty bad fever so the first part of my season has been pretty rough,” said Williams, a 2011 T&G Super Team All-Star. “I haven’t really been running. I’m just trying to rest.” The Colonials dropped their opener to powerhouse Wachusett Regional last week, but Williams hoped he’d be able to compete in Saturday’s Amherst Invitational. “If you’re sick, you’re sick — it happens,” Williams said. “Coach (Jim Smith) tells me when anything happens like this, you’ll bounce back. There are times when I may not perform my best, but I always have a positive attitude.