fever in 2 month old for 10 days

My sweet girl has had a fever over 100.4 off and on for 10 days.  She is sleepy her poop smells really bad and her eating habits have changed she is not eating as much.  We have been to the dr several times and the hospital once they ruled out UTI and kidney infection.  She hasn't been to dehydrated but a little.  One nurse said she thought it was rosella but it should be done.  I'm going crazy. I'm so worried about her but the doctors don't seem worried because they say she is over 2 months and she should be fine.  Anyone have any ideas?