Still hospitalized three days after having a seizure, Kelly Osbourne's doctors are trying to figure out the cause of the incident.

On Thursday (March 7) the 28-year-old was on the set of her show “Fashion Police” when she told co-star Melissa Rivers that she wasn’t feeling well before falling to the floor.

After being rushed to the hospital, the purple-haired fashion critic thanked fans for their concern, tweeting, “Thank U all 4 UR beautiful well wishes yes I did have a seizure they are just trying to figure out why?”

Kelly’s mom, Sharon, also updated folks on Friday with “I want to thank everyone for their concern about @MissKellyO. She's doing fine she's at Cedars and is surrounded by the best doctors & love.”

According to a report from TMZ, doctors have been running tests to determine if the seizure was an isolated incident, or if it could be a sign that Ms. Osbourne has epilepsy. Check back with GossipCenter often for the latest.