The reality star, who is battling cervical cancer, is said to have fainted after her latest session of chemotherapy.
'Jade has gone through an awful few days and has been very ill,' says a source.
'She collapsed at the end of the week and had to go back into hospital.
'She is a fighter, but the treatment has just taken everything out of her and she has been in excruciating pain.'
Jade, 27, is determined to recover from her latest setback in time for a 'welcome home' party for boyfriend Jack Tweed, 21, who was released from jail last week.
'She has been in a lot of pain and she is going through hell,' her spokesman Max Clifford tells The Sun.
'It is a battle for life, but her condition has not worsened and treatment is ongoing.'
Where to next?
- What Jade's cancer battle can teach us
- Get all the facts on cervical cancer
- Read Sara's story about how she survived cervical cancer