BOSTON - The Tyler Thornburg injury saga took another turn on Saturday

Manager John Farrell revealed that after Thornburg's most recent throwing session the reliever felt more discomfort and fatigue.

Though he's made 60 to 70 throws up to 150 feet on flat ground, Thornburg has not yet thrown off a mound and continues to feel symptoms related to the shoulder impingement that initially put him on the disabled list at the end of spring training.

"Everything is being explored," Farrell said. "Whether that's further imaging, whether that's testing done in certain ways or whether there's nerve testing that is explored -- we're trying to exhaust all avenues that are available to us."

Farrell was quick to clarify that by putting the nerve damage issue out there, he didn't want that to become the diagnosis. Rather team doctors are exploring all options in an attempt to find the root cause.

It's likely another MRI will be taken. An initial MRI at the beginning of the season revealed no structural damage, just the impingement.

"We're a couple months down the line here and still dealing with some things that aren't allowing him to get over the hump and back on the mound," Farrell said. "You seek all potential options available to you.

The Red Sox traded Travis Shaw, infield prospect Mauricio Dubon and minor-league pitcher Josh Pennington to Milwaukee this winter in exchange for Thornburg.

--

Follow MassLive.com Red Sox beat reporter @jcmccaffrey on Twitter. She can be reached by email at jmccaffr@masslive.com.