UPDATE -- 6:06 p.m.: CBS News reports Beau Biden is undergoing tests at the MD Anderson Cancer Center at the University of Texas. An earlier CBS report said that Biden had been admitted to the cancer center, as opposed to just undergoing tests. They have since issued a correction.
Below, more from the AP:
WILMINGTON, Del. -- Delaware Attorney General Beau Biden was undergoing medical tests on Tuesday in Houston, where family members, including his father, Vice President Joe Biden, were gathered.
The younger Biden, who is being evaluated to determine why he experienced weakness and disorientation last week, posted a smiling photo of his wife Hallie and himself to his Twitter account Tuesday morning.
"Touched by all your well wishes--thank you. Nice evening in Houston w/ Hallie; will share update when we have it," the tweet read.
Beau Biden, who suffered a mild stroke in 2010, began experiencing the symptoms last Wednesday night after driving to Indiana for a family vacation, said Jason Miller, a spokesman for the Delaware Department of Justice.
Biden, 44, was initially admitted to Northwestern Memorial Hospital in Chicago and traveled the next day to a Philadelphia hospital to consult with his doctor. He was discharged and spent the weekend at home in Wilmington.
Miller said Biden currently is undergoing testing in Houston to determine the cause of his symptoms, but declined to say exactly where the testing was being done.
In Washington, White House spokesman Josh Earnest said President Barack Obama spoke by phone over the weekend with Joe Biden to offer his best wishes for the family.
"A lot of people all across the country woke up with Beau Biden on their minds," Earnest said.
The White House said the vice president had been home in Delaware for the past several days and accompanied his son to Houston. It's not clear how long the vice president will stay, but he's scheduled to join Obama in Scranton, Pa., later this week during Obama's two-day bus tour.
The younger Biden's Twitter account on Sunday posted a photo of him and his father sitting on a porch and smiling while sending a message of encouragement to a Delaware team that was in the Little League World Series.
This isn't the first health scare for Beau Biden, who became Delaware's attorney general in 2007. After a mild stroke in May 2010, he spent a week in the hospital and more than a month recuperating at home.
"Stroke was the farthest thing from my mind when I went in," Biden said at that time.
Biden's father has had health scares of his own, including a life-threatening brain aneurysm in 1988, when he was 45.
Associated Press writer Josh Lederman contributed to this report from Washington.