Portis saw the same doctors who examined Eagles back Brian Westbrook, who has suffered two concussions in the last month. Portis was hurt two weeks ago against Atlanta. He did not play last week against Denver and has been ruled out for Sunday's game at Dallas.
"We're going to make sure we take care of all the details. We're for Clinton getting well," coach Jim Zorn said. "Each day Clinton's done a great job of communicating how he's felt, and that's what it's going to take.
"I want to be involved with those conversations, not so much to see 'how fast can we get him back,' but just to make sure the young man is improving and getting better."
Portis gave his own update via Twitter: "Hey fans! Trying to get healthy to finish the season strong, want to make sure there aren't lingering affects before returning to the field."
Defensive tackle Albert Haynesworth is questionable for Sunday's game because of a sprained left ankle, although Redskins secondary coach Jerry Gray said Friday on "The Michael Irvin Show" on ESPN FM 103.3 that Haynesworth would play.
Haynesworth, who has 42 total tackles -- three sacks -- and 19 quarterback hurries this season, was unable to practice this week. He tested his ankle on a treadmill on Friday.
If he takes the field, Haynesworth will be lining up across from Cowboys center Andre Gurode for the first time since 2006, when Haynesworth was suspended five games without pay for stomping on Gurode's forehead -- the longest suspension for an on-field infraction in league history.
The wound took 30 stitches to close.
Both Haynesworth and Gurode have insisted this week that the two players have since become friends.
"We have been talking and everything," Haynesworth said earlier this week via conference call. "We even went out together. So, yeah, we are cool."
Information from The Associated Press and ESPNDallas.com was used in this report.