any advice ? I get very dizzy and exhausted while walking long periods of time .. I wasn't like this…

any advice ?

I get very dizzy and exhausted while walking long periods of time .. I wasn't like this before but ya know pregnancy.. anyway tomorrow I have an ultrasound and than my sister is taking me to look at where I'm having my babyshower than we are going baby shopping than probably out to eat ..it doesn't sound like a lot but I get dizzy and feel like fainting walking through Walmart for 30 minutes . I'm bringing my water bottle full of ice and water (duh),but is their anything else I can do before ? or if I get faint again?