Katie Price is suffering from a mystery illness.

The 35-year-old star, who has four children, Harvey, 11, Junior, eight, and Princess Tiaamii, six, and a four-month-old baby boy, Jett, was temporarily hospitalised earlier today (22.12.13), but her doctors still have no idea what is wrong with her.

The former glamour model admitted she was feeling very ''poorly'' on Twitter, writing: ''Still soo poorly problem getting worse no meds are helping such s*** times (sic)''

She later tweeted: ''Great in hospital on a drip''

The brunette beauty gave no hint about the cause of her ''nightmare'' and was allowed to return home for two days but is due to return to hospital to undergo an MRI scan on Monday morning (23.12.13).

She tweeted: ''Out of hos go back again in 48 hours mri scan had morning of needles my worst nightmare, time to concentrate on getting ready for Christmas (sic)''

Katie first revealed she wasn't well on Wednesday (18.12.13), writing: ''Feeling sooo poorly still, im just not getting better doctors again this morning (sic)''

The 'Love, Lipstick and Lies' author has been in and out of hospital a lot in recent months.

She was rushed to a medical centre in September for emergency surgery just weeks after she delivered her fourth child in traumatic circumstances.

Jett, whose father is Katie's third husband, Kieran Hayler, was born eight weeks early in August through emergency caesarean section in a French hospital after she caught an infection.

The baby's heart rate dropped to a dangerously low level, and he was taken into an incubator as soon as he was born.

Speaking after the birth, Katie: ''Bringing life into the world is supposed to be magical. But what I went through was a nightmare.

''The only thing that had got me through the nightmare was the thought of cradling my little boy.''