By DAVID WRIGHT and ROBIN MIZRAHI

Britney Spears is facing fresh heartache over baby Sean Preston amid fears that he could suffer long-term brain damage. When seven-month-old Sean toppled out of his high chair and fractured his scalp it wasn't his first fall, an ENQUIRER investigation has uncovered.

Twice before, says a source, the baby has rolled off of the pop princess' bed and crashed to the floor. That's one of the shocking new claims about Britney's bizarre life uncovered by The ENQUIRER — and, tragically, it comes as doctors say Sean could suffer brain seizures or memory loss for years to come.

The insider also claims:

Britney is terrified that three former bodyguards are poised to tell all and reveal devastating details of her drug past, her bawdy sex life and her stormy marriage

She sleeps in till 2pm — and she's a sloppy housekeeper who lets her three dogs soil the house

She exploded in rage after finding a drug dealer with hubby Kevin Federline in their home

The ENQUIRER reported exclusively last week that Britney was grilled by child welfare officials about neglect allegations after Sean fell backwards out of his high chair on April 1. Now we've uncovered details of two other mishaps when he rolled off his mother's bed.

"Both times Britney freaked out when she was wakened by the sound of her little boy screaming," said an insider. "She found him lying face down on the floor after falling from the bed.

"It was every mother's nightmare come true. She was so afraid he was hurt. The first time it happened, Sean was just over three months old. Fortunately the floor in Britney and Kevin's bedroom is carpeted and the baby was frightened but uninjured.

"But two weeks later, the same scary thing happened again. Once again Britney woke to find the little guy face down on the floor, crying his heart out. This time she was shaken to the core."

Pick up this week's issue of The ENQUIRER to read the rest of this story!