Katie Price has fractured her coccyx.
The former glamour model - who has children Harvey, 13, Junior, 10, and Princess, eight, from previous relationships and Jett, two, and Bunny, 16 months, with husband Kieran Hayler - was left in agony after accidentally injuring the base of her spine while playing with the kids.
She said: "I fractured my coccyx a few weeks ago.
"They were all messing around in Junior's room a few weeks ago and I came in and jumped on the sofa arm, right on the hard bit.
"I was in so much pain and the next morning I couldn't even move.
"Kieran wanted to call an ambulance! We managed to get there ourselves, but you should have seen the way I was walking."
Katie adores horseriding and her young son Jett already shares in her passion.
She told Britain's OK! magazine: "When I go to feed the horses he carries the food bowls in and he puts them down and then kisses each horse. Even the big ones."
Kieran added: "He's got a little handle on the saddle which he can hold on to."