Is something wrong?? 19 weeks pregnant

So for the past week all of a sudden I keep feeling very weak soon after I wake up eat and get to work. It also continues on and off through out the day. I feel like I’m going to pass out and when I sit down it gets better. But when I get back up I feel nauseas and tired and just over all icky. I also constantly feel like I’m starving and even after I eat and feel full I still feel like I need more. But whether I eat or not I can’t seem to stop feeling terrible. Has anyone had anything like this?? Or heard of it??