Almost passing out at walmart

Today I wanted to go out to Walmart with my husband to pick up a couple of things as we are leaving I get so hot I can barely stand it and I feel like iam about to pass out! I told my husband and he told me to sit down at the bench and got me a water and went to go get the car. Iam almost 16 weeks pregnant I am constantly so tired I cant do much. Wonder if I should go to the doctor?