Daisy has done this twice now in the past couple of months. It always happens early in the morning. She'll wake me up making that doggy heaving sound. Luckily I have been able to get her into the bathtub both times before she threw up. The first time she threw up once, but this morning it was twice. It seems to be nothing more than stomach bile (TMI sorry). Any idea why this is happening? She seems to be fine otherwise, eating normally, peeing, and pooping normally.