Vomiting

I just fed my 5 month old her bottle and just when I started to burp her she threw up what looked like all the milk I fed her. It was quite forceful and definitely different from spitting up as there was a vomit noise and it was so much. What could be the problem? Do you think I should call the doctor or wait another day to see how she goes? She was also very fine and not upset at all after she threw up and she has no fever