The Queen's sickness was first announced on Friday, and she spent yesterday resting at Windsor.
Her Majesty had been due to attend a Welsh military celebration in Swansea during the country's St David's Day celebrations on Saturday, but was forced to cancel the plans.
The Queen, who is 86, has undertaken a number of engagements during the last week.
On Tuesday she met the Archbishop of Canterbury at Buckingham Palace, and on Thursday she presented a host of Olympic stars with honours during an investiture ceremony.
More top news
A 93-year-old Second World War veteran has flown over 10,000 miles to be reunited with his wartime sweetheart more than 70 years on.
The Republican presidential candidate is known for making some "interesting" comments - but can you guess who made these?
Twitter has announced changes to its timeline which will mean you see the "most important" tweets first.