Red Sox pitcher Clay Buchholz has been placed on the 15-day disabled list Sunday with a gastroinstestinal problem.

According to the Boston Herald, the issue is serious enough for Buchholz to make a trip to the hospital.

Aaron Cook was activated from the DL and started Sunday's game against Atlanta in place of Buchholz.

Once a highly regarded prospect for Boston, Buchholz has turned in a less than impressive 2012 season. Despite winning his last four starts and sporting an 8-2 record, he has a 5.53 earned run average, far lower than it stood in April or May.

After allowing at least five earned runs in each of his first six starts, Buchholz has pitched closer to expectations, going 5-1 with a 3.35 ERA in his last eight starts. His run of success culminated with a shutout of Baltimore on June 7, but he gave up five runs in six innings during his last outing on June 19.

The oft-injured Cook has started only one game for the Red Sox this season and allowed seven runs in 2 2/3 innings.