"It's very obvious that she is not 100 percent well," a source who saw Bynes at her Thousand Oaks gym over the summer tells PEOPLE. "She is still obsessed with her body and spends more time in front of the mirror than she actually works out. She doesn't like when people look at her and has even confronted a few other members."
A second source adds that she appeared to be unhappy about being under her parents' court-ordered conservatorship.
"Her parents were closely monitoring her, including her driving," says the source of Bynes, who got her license back in April. "She would have arguments with her dad in the car."
The conservatorship ended in June, according to her father, Rick Bynes, who told x17 he has not seen his daughter since.
"She's 28, she does what she wants," he said. "We don't know a thing."
Several Twitter users spotted Bynes leaving John F. Kennedy International Airport and heading back to Los Angeles on Sept. 25.
"Amanda Bynes, with ridiculous purple hair, is at the gate freaking out about her missed flight to LA," Jason Persse Tweeted. "Get me the hell out of JFK."
As for Bynes's current whereabouts, she had been enrolled in the Fashion Institute of Design & Merchandising, but a source says she hasn't recently been spotted attending classes.
Representatives for Bynes could not be reached for comment.
Reporting by PERNILLA CEDENHEIM