Thomas, who has been on the disabled list with a torn tendon in his right quadriceps since May 29, visited a Los Angeles-area specialist on Tuesday afternoon. He was told to get another MRI on his massive right thigh and come back in a week for another chat.
"Like I said [Monday], he's a cautious doctor," Thomas said. "He's not going to rush anything, and as much as I want to get going, I have to listen."
Despite not being cleared for any baseball activities, Thomas planned to remain with the team for the rest of the three-game series here against the Angels and make the trip to Oakland for a four-game series that opens on Thursday.
"Frank's such a great guy, just having him around is a good thing for the team," A's manager Bob Geren said.
Thomas, 40, said the upper-body workouts and bike work he's been doing at home in Las Vegas, along with trips to his in-home steam room, have kept him at his playing weight of 275. He conceded that he'll need a Minor League rehab assignment before rejoining the A's and remains hopeful that he'll be activated sometime this month.
Mychael Urban is a national writer for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.