please help.

I will be 15 weeks pregnant tomorrow with my first baby. I have had kinda light kinda heavy bleeding since Thursday night, also have went through 1 1/2 pads since then. I have cramps in my lower abdomen and was little light headed yesterday and I see my OB on Wednesday going to call him again tomorrow since no one has called me back since I've been trying to call and see what he thinks I should do but should I be worried or is this normal...