If you are breastfeeding, their bodies digest it much better than formula and she may not poop very often. My sister's babies would both only poop about once every 5-7 days when they were being breastfed.
If you are formula feeding, then you may want to try a different brand. Enfamil was notorious for making DD1 cranky/ constipated. She did much better with good start.
It could be what you are eating as well,my little girl and I had the same problem,she would poop daily,then she didn't for 3 days,I know it isn't anything compared to two weeks,but I guess you just know when something isn't quite right with your baby-- Anyhow,it ended up being what I ate,or thats what i believe because as soon as i went back to a lot of fluids and soups,she started her normal bowel movements and was less fussy. Also formula,I had trouble with her latching so I went back and forth with formula and breast milk here and there...I really don't think she liked that/: Well,Hopefully your doctor figures what's going on and that she feels better,I know how upsetting it is not knowing exactly what's happening.