Alberto E. Rodriguez/Getty
09/04/2008 AT 06:45 AM EDT
Jennie Garth may be reprising her role
as the stylish Kelly Taylor on the new 90210
, but earlier this year, looks were the last thing on her mind.
"I had this six months of hell," the actress, 36, tells PEOPLE. "I had a sick daughter and then my father passed away, so there was a six month period in my life when I didn't think about my looks or my weight or my body or anything."
Fresh off her stint on Dancing With The Stars
– and toned from months of 8-hour-a-day dance practices – Garth suddenly faced every mother's worst nightmare. Her 5-year-old daughter Lola, "got very sick and we didn't know what was wrong with her," says Garth, who has three girls with husband Peter Facinelli. "I was basically locked in a closet with her for three months."
Leaving all vanity behind, "I didn't exercise or eat healthy," she adds. "I had been a 27 in my jeans after Dancing With the Stars
and I was so excited. But it really went back quickly. I definitely gained inches and a size."
Finally, doctors were able to diagnose her daughter's ailment. "It turned out to be a form of JRA [Juvenile Rheumatoid Arthritis]
and we treated her and it's in remission," says Garth. "It was tough, but she's better now." RELATED ARTICLES:
2007: Jennie Garth invites PEOPLE into her home
1992: Jennie hits it big in 90210!