Demi Lovato is struggling through shows on her European tour as she battles a stomach bug.

The Heart Attack singer is performing as a support act for Enrique Iglesias, and she has now explained to fans why she could hardly dance or move around the stage during a gig in Glasgow, Scotland earlier this week (beg23Nov14).

She writes in a post on Instagram.com, "Some of you may have been wondering why I was barely moving on stage in Glasgow... Fighting a tummy bug. Thanks for being an amazing crowd anyway!! Birmingham - you were amazing crowd as well!!"

Lovato also battled homesickness on Thursday (27Nov14) as she spent the Thanksgiving holiday away from her family.

She writes, "Happy Thanksgiving... Missing my family a lot today... I love them so much and I'm so thankful for them."

Lovato is scheduled to perform at London's O2 Arena on Friday (28Nov14).