my cavalier king charles is 1.5 yrs old. bought the food the breeder told me to buy. she did fine for 4 days and now vomits later in the evening. she is fed 1/2 c food 2 times daily. told not to over feed her and she is given no people food. can't understand what this is about. not enough food??? poops ok but pees very little, but also drinks very little. any ideas anyone???