Contractions

I thought I was having braxton hicks contractions but i went to my anatomy scan the next day and I was still having contractions off and on and had one during my ultrasound. They didnt seem too concurned the just told me to rest and prop my feet up ans drink water if I have one unless they seem petsistant then go to L and D to be monitored for an hour or two. Anyone else had this happen to them? Im an iv infusion therapist so im on my feet for 10-12 hours a day moving around.