Green poop and constant crying

My LO (little one) is 6 wk she Ian on cow and gate first milk the pre made. She has been crying none stop and i have done all the useually the nappy change the feed and burp but she won't stop. Her poo is useually a mustard colour but when I can chnaged earlier I was  bright green colour? the health visitor came and said she has a hernia but it's is very common she isn't normally a sickie baby but she has been being sick quite often after feeds and then will ask for more this has been going on for about 2 week now  

Just wondering has anyone got any idea what may Ben wrong with her and should I be worried? 

Thank you and much love x