J.S.
My daughter is 7 weeks old and has the same problem. She has reflux bad and we are trying several medications with her doctor to get things under control. She hasn't been gaining weight to well either. Deffinately mention it to your doctor. I would not put cereal in her bottle while she is this young unless your doctor thinks it is a good idea but generally it is not for babies this young. Her digestive track may be immature and adding something harder to digest may cause more problems. Holding your baby upright after feeding will help as well as keeping the booger bulb close by to suction out the spit up from her nose. You'll soon recognize her facial expressions for when she has a bubble and is about to errupt. Pick her up and burp her. Best of luck.
J.