Sonnanstine said the problem has bothered him since the Rays played the Yankees in New York on July 18.
"Other than that, just trying to get through it," Sonnanstine said.
The Rays used Hellickson for one start only before optioning him back to Durham after Monday's 4-2 win. Sonnanstine will be eligible to return on Saturday against the Blue Jays and he said he feels as though he'll be ready by then.
Sonnanstine said the problem has been nagging him "a little bit for a while now.
"But we got to a point where we needed to address the issue," Sonnanstine added. "[My] arm felt great, and I was available. But the nice thing about our starters is they've been going really deep. And with my role being the long guy, I haven't really been needed.
"[When you play a] 162-game season, you're going to have nicks and bumps all over the place. You try to minimize the damage as much as possible. This is probably the wise decision."
When Sonnanstine was asked if he thought he could have pitched through his problem if the Rays had not made the roster move, he answered: "That's a good question. I guess we'll never know."