Bad Feeling

For the past few weeks I've been feeling like something is wrong. This is my forth pregnancy and I haven't had this feeling before. I haven't had any of my usual pregnancy feelings, like feeling the baby move by now even just little flutters or sickness to the point that I've lost 10-30 lbs in all my previous pregnancies. I'm 17 weeks and a little worried. I just feel like I'm crazy or something.