Billie Piper feared for her son's life at Christmas.
The 27-year-old actress was left terrified when Winston - her 15-month-old child with husband Laurence Fox - struggled for breath and was unable to get answers from medical experts as to what was wrong with him.
She said: "We really panicked, he was having trouble breathing, I had quite a big fright with him... they wouldn't tell us what it was."
Billie also admitted that she and Laurence are undecided as to whether have more children and says she finds motherhood a struggle.
She told British TV talk show host Jonathan Ross: "It's probably too soon to think about having another but you always have it in your mind once you've had one. We were considering an only child, but it sounds a bit cruel.
We really panicked, he was having trouble breathing, I had quite a big fright with him... they wouldn't tell us what it was.
"It's tricky at times... I'm a competitive mother."
Meanwhile, Billie - who shot to fame aged 15 with single 'Because We Want To' - insists she has no plans to ever return to her music career.
She said: "I don't have a great voice, I was basically a charlatan, just faking it really."