Hi can I use cremaffin syrup while bresrfeeding my baby is just 18 days... Does cremaffin effect baby on brestfeed??

Cremaffin syrup. Cremaffin syrup is a oral laxative and is not absorbed into the body. Safe to use while breastfeeding.
No. The laxative you mentioned should not affect the baby. However, you may wish to use a fiber laxative like Metamucil and drink plenty water so that your urine is mostly colorless. You may also increase your intake of fiber foods. Consult this site for fiber foods.
http://www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/in-depth/high-fiber-foods/art-20050948.
Stool softener . Looks like you can nurse while on it.