Feeling weak..

I'm 8w3d..fingers crossed I've had a pretty easy 1st trimester so far. Some nausea and vomiting-but not the end of the world.  Recently I have been getting super dizzy and just feel entirely drained. No color in my face and I just feel like I have nothing in me. I also started getting (TMI) horrible diarrhea- I'm talking bent over, sweating, cramps bad. Should I call the OB? I can't tell if this just another one of those pregnancy symptoms or what. Help!!