I kinda think their reaction is a bit odd myself, but I guess you should be thankful they're thorough! ;) It could absolutely be teething, although to be honest, she would be on the young side of teething. Her symptoms do indicate teething, so it's possible, but both my kids exhibited similar symptoms from about 4 months and no tooth appeared until 8-9 months. The mucus poop sometimes happens to my kids randomly too...it's usually only once or twice and then nothing more. If I only see if a few times I don't call the doctor, BUT...it could also be a sign of C-dif. I'm not sure it's real name, but it's a virus/bacteria (not sure) that causes the runs and it can be very difficult from which to recover. I would bet that's why the doctors were wanting to run tests, and it can be pretty bad for a baby that young, but if the tests came back negative you have nothing to worry about...I might just ask them if that's what they tested for though.