Jessie J Speaks Out About Her Mystery Illness At Wireless Festival

Jessie J defied doctor's orders and took to the stage at Wireless Festival this weekend.  Although she had previously warned that she would not be her "usual crazy self" at the gig, the "fragile" but determined star pushed through to perform for her fans. The singer looked fighting fit at Wireless Festival.  The Bang Bang singer has not revealed the details of her illness, but did make reference to it throughout her energetic performance. She told the crowd: "Please forgive me if I’m a little unsteady on my feet. The doctors told me not to come here today. "My brain is telling my body to do one thing – but my body is doing the complete opposite. This is my first show in one month."

Getting ready for wireless today | ?

A photo posted by Jessie J (@isthatjessiej) on Jul 5, 2015 at 1:20pm PDT

  The star performed for the first time since her mystery operation (image via Instagram). Following the performance, in which she belted out the set list from her current Sweet Talker tour, the star took to Instagram to express her gratitude. She gushed: "I felt so lucky to be on stage today. "It took everything I had but I did it, I did it. Thank you #wirelessfestival."

I felt so lucky to be on stage today | If you had seen me last week | No one in my friends and family thought I would bounce back for this show (inc myself) | It took everything I had but I did it | I did it | Thank you #wirelessfestival ?? A photo posted by Jessie J (@isthatjessiej) on Jul 5, 2015 at 2:14pm PDT

The 27-year-old first sparked concerns about her health two weeks ago when she posted a photo from her post-op hospital bed, later writing "I am not ok".