baby movement

Does anyone's else's little ones move more on certain days. My baby boy will one day move constantly all day, and then not as much the next day or two, and then constantly again. It's like a Pattern and it scares me and stresses me out. I do feel him hiccup about 3 times a day, and I do get him to move if I drink cold water or poke at my stomach on the days he is not as active. Are there any other mommies who are going through the same thing? I have an ultrasound wed, and dr appt Thursday so im going to bring it up. Please tell me I'm not the only one.