The troubled actress was only discharged from treatment for schizophrenia and bipolar disorder last week, but is said to have enrolled for classes at the Fashion Institute of Design and Merchandising (FIDM) in California, a move psychiatrists have advised against.
A source told RadarOnline.com: "Amanda was told by her doctors that going to fashion school, so soon after being released ... [is] an absolutely terrible idea for her to do at this time - it's almost setting her up for failure.
"There will be pressure on Amanda as far as school work, deadlines, and it's unlikely she will be able to succeed.
"The fashion school she is enrolled in is in Orange County, almost two hours from her parents' house, and she still doesn't have a valid driver's license."
Amanda is back living with her parents, Rick and Lynn, who has been granted conservatorship of her daughter, but the source thinks she should consider returning to her studies more slowly.
The insider added: "Amanda's treatment team felt that she could have benefited from further inpatient care.
"She is still seeing her doctors on an outpatient basis, but this is all happening way too fast and too soon. Amanda should be eased back into her life in a controlled manner, because she is dealing with a very serious health diagnosis. Why does she need to enroll now in school? It would be ideal if she waited six months to a year."
Amanda, 27, was placed under an involuntary psychiatric hold in July when her erratic behavior spiraled out of control, culminating in a bizarre incident during which she started a small fire in a stranger's driveway in Thousand Oaks, CA accidentally setting fire to her own trouser legs and dousing her pet dog in petrol.