United Kingdom, June 9 -- Jessie J was left in floods of tears after suffering a panic attack on the "worst day so far" following her breast cancer diagnosis.

The 37-year-old pop star went public with her health issues last week revealing she is battling an "early" form of the disease and is currently undergoing tests before surgery later in the year - and now the mom-of-one has revealed she has been feeling overwhelmed as she comes to terms with her health crisis.

In a message posted on Instagram, she wrote: "Honestly, had my worst day so far yesterday since my diagnosis and the busiest three months I have had in years. Work. Toddler. Cancer. life etc had my mind [drained].

"'Panic attacks/ tears. big fears/ anger/ overwhelm bad. [sic...