Help! My baby cried all day today!

Molly

My baby girl is 3.5 weeks old and has been super fussy the past couple days. I could hear rumblings in her tummy so we bought gas drops, which seemed to work yesterday but have not seemed to make a difference today. She has been pretty miserable today, like she can't get comfortable. She cried for close to 8 hours, off and on. I would get her comfortable, put her down, and the whole process would repeat. I've ruled out dirty diaper, too hot/too cold, over/under stimulated, position change, etc. She does act hungry (rooting, chewing on hands), but does not stop, even if belly is full. She will just eat and eat and then vomit. We have been giving her 2 or 3 oz bottles every 2-3 hours. I really feel helpless and feel bad for her! I want my happy baby back!