United Kingdom, Aug. 3 -- Jessie J has been readmitted to hospital with fluid on her lungs.

The 37-year-old pop star - who underwent surgery for breast cancer six weeks ago - has revealed via social media that she's been readmitted to hospital and told that she has an infection.

Jessie said on Instagram: "6 weeks post surgery and I was back in the same ward I was after my surgery. Not expected or planned.

"I had and still have symptoms that pointed towards a blood clot on the lung. IT IS NOT A BLOOD CLOT THANK GOD.

"They ran a lot tests, which ended up showing I have an infection (still trying to figure out what) and a little fluid on my lungs.

"Finding it hard to breathe in, but I discharged myself last night (I hate being in hospit...