Fonty
Vomitting disgusting stuff is fairly common. I've had it also. Thing is though I didn't have it on my thirty day fast many years ago but I have had it on shorter fasts recently. I put it down to the fact that my diet was much healthier back then. So the excess detox and particularly the bile is a result of eating either too much chocolate or too much soft drinks or both! They were the main difference in my diet from my 30 day fast.
Anyway, if you can stick it out you will find relief soon, hopefully within a day or two. It can get pretty distressing though. If you do end your fast because of it be careful to end it correctly- it can be very tricky ending a fast mid crisis.
Take care,
Andrew.