Hi ...I Had A Bout Of The Runs ..lasted 2

Hi ...I had a bout of the runs ..lasted 2 days. .then no bm for 5 days, lived on dry toast and bananas, then a bit of chicken and rice ..then yesterday had a bm ...normal but later had lunch ..then dinner of pasta prawns in cream sauce ..now the runs again ...I have Hashimotos. ..and recently noticed mybowels have changed..harder to go than normal ...this is the 1st time Ive had this in 10yrs ...last time was diagnosed with giardia ......could this be that ? Pamela