Why won't my newborn stop crying?

She all of a sudden won't stop crying. Was asleep for a half an hour but other than that she has been awake for almost 4 hours. She has lately been very fussy and I can't figure out why. When I try to nurse her, she get overly excited and cries. She doesn't have a dirty diaper, she has been burped, I gave her Mylicon, I walk with her, my mom is rocking her in the glider, nothing is working and I am loosing it!!!! For the past 4 days the only way to get her to sleep is to way down with her and nurse her to sleep then she will wake up an hour or 2 later; which isnt like her. She needs atleast four 3 hour naps a day or she is a cranky . At night she is usually a great sleeper but lately she is just a handfull! The first week she was home she was great but now im just getting exhausted and worried something could be wrong with her. And because she is so young I won't let her cry herself to sleep. PLEASE HELP!!! ANYTWAY TO GET HER TO SLEEP WILL BE GREAT!!!