Riley, first of all forget any mention of suppressors or muzzle brakes. Neither is allowed by NRA highpower rifle rules.
Second, I'm assuming by the number of rounds, caliber and bullet weight that you were shooting a mid range prone match? Is that correct? And if so, were you shooting prone with a sling or F class with a bipod?
If you were shooting with a sling, were you wearing a proper shooting coat? Do you have a local shooter that can give you some basic position and technique coaching?
Does the rifle you used have any adjustments in the stock?
These issues are so hard to diagnose and assist on the internet. Particularly when most of the people on this site have never shot the sport you're doing. Their advice, while well intentioned, might not be too helpful.
At the end of the day, if you are brand new to shooting centerfire rifles, there will be some very minor soreness from lying in prone and from the recoil. Your body has to adjust to it all. However, you should not be in pain.