S.B.
I agree that it could be a bug that's making you feel sick. Also, the sharp pains could be gas or constipation. Make sure you're getting enough fiber in your diet and drinking plenty of water (should help the headaches, too!). I'm expecting number 2 in 9 weeks and had a harder time with "evening" sickness this time.
I also agree that if you're really worried about your symptoms, it never hurts to call your care provider and discuss it with them. They can decide whether you need further evaluation or put your mind at ease and give pointers for common pregnancy discomforts (I understand them being more "uncomfortable" with subsequent pregnancies and therefore more worrisome).
Hang in there, and I hope you're feeling better soon! God bless you.
p.s. Try ginger ale or diet 7-up to settle your stomach. I hated ginger ale with my first, but loved it with my second. Also, try your water or decaf tea with LOTS of fresh lemon. It's refreshing and soothing to me.