Lookin' good, Amanda!

Recently rehabbed actress Amanda Bynes looked happy and healthy in a series of vacation bikini shots she posted on Twitter over the weekend.

"Spring break," she captioned one photo of herself, clad in a neon-yellow bikini and relaxing on a lounge chair.

Bynes, who is vacationing in Mexico, also thanked her fans for their birthday wishes -- she turned 28 last Thursday.

In December, Bynes left a psychiatric facility following a very public meltdown. On March 1, she returned to social media, which in the past had been a forum for her to rant about other celebs, with positive tweets about her life.

"Hi everyone! I'm busy studying at @FIDM but I want to say I love you to my fans! Xoxo Amanda," tweeted Bynes, who is studying at the Fashion Institute of Design & Merchandising in California.