IS MY BBY LACTOSE INTOLERANT?

MY BBY IS 7 WEEKS AND I BREASTFEED HER, THE LAST FEW DAYS SHES BEEN CRYING LIKE SOMETHING IS HURTING HER SHE HAS GAS REALLY BAD, SHE IS TAKING ZANTAC FOR REFLUX, SHE SPITS UP ALOT, IVE TRIED GIVING HER GOOD START FORMULA AND SHE SPITS UP MORE, SHE WONT USE THE BATHROOM FOR 2 DAYS.....I THINK SHE HAS COLIC....... SOMETIMES SHE WILL NOT TAKE MY BREAST.... IM WONDERING IF I SHOULD ASK HER DR IF I COULD TRY NUTRAMAGEN FORMULA....HAS ANYONE HAD THIS PROBLEM WHITH ANY OF THEIR CHILDREN????????