The club will report more about prognosis after Hellweg's appointment next week with Dr. James Andrews renders a second opinion, Ash said.
Hellweg last pitched Sunday in Omaha, allowing two earned runs on four hits in 3 2/3 innings, with one strikeout and five walks. He felt a pop in his elbow and threw nine more pitches before leaving the game.
"There were no warning signs of any kind," Ash said.
Hellweg joins a growing list of professional pitchers dealing with a serious elbow injury this season, including the Rays' Matt Moore and the Yankees' Ivan Nova most recently. Brandon Beachy, Patrick Corbin, Kris Medlen, Jarrod Parker and Jameson Taillon are among those who have already undergone Tommy John surgery in recent weeks.
"I don't know if I'd call it an epidemic, but it's certainly been an injury of note this season," Ash said. "We had two [Tommy John surgeries in the Minor League system] last year. We're probably on the lower number of clubs in this over the last four or five years."
The Brewers are regarded as one of the clubs on the cutting edge of injury prevention, particularly for pitchers. For the last decade, Raasch has led a biomechanical analysis program at Milwaukee's Froedtert Sports Medicine Center, compiling a database of professional pitchers after taking measurements of their deliveries with eight high-speed cameras and 42 digital markers. They measure the forces applied to a pitcher's body while throwing a baseball, and Raasch and the Brewers use that data to avoid shoulder and elbow injuries.
Brewers medical director Roger Caplinger also launched an organization-wide study in 2011 that charts pitchers' range of motion, looking for red flags that could cause injuries.
The 25-year-old Hellweg came to the Brewers from the Angels along with shortstop Jean Segura and right-hander Ariel Pena in a July 2012 trade for Zack Greinke. He was the Pacific Coast League pitcher of the year in 2013, going 12-5 with a 3.15 ERA, but struggled in a Major League callup.
He began 2014 back at Triple-A Nashville and was 1-2 with a 4.95 ERA in four starts.
Adam McCalvy is a reporter for MLB.com. Read his blog, Brew Beat, and follow him on Twitter at @AdamMcCalvy. This story was not subject to the approval of Major League Baseball or its clubs.