Is It OK To Feed Your Dog Crackers If He Is Throwing Up Yellow Bile? Was This A Good Idea? And What Should I Do If It Happens Again?

Bubblez888,
 
When a dog starts vomiting further stimulus (like crackers) to the stomach needs to be avoided.  Feeding a vomiting dog can cause more vomiting.  Please do not feed your dog for 12 hours to let the stomach settle down.  I would also withhold water for 6-7 hours to again avoid re-starting the vomiting.  Re-introduce water small, frequent amounts at a time. 
If your dog vomits more than 2-3 times, starts having diarrhea, becomes lethargic, and has no interest in food or water please have him seen by a veterinarian.
If he has not vomited in 12 hours feed him a bland diet--boiled chicken or hamburger, boiled rice, cottage cheese--these things are very easily digestible helping to settle the stomach.
Pepcid can also be given at a dose of 0.5milligrams per kilogram of body weight or 0.25 milligram per pound of body weight.  This acts as an ant-acid reducing nausea and vomiting.
 
Ann Falk, DVM

The best thing you can do is take him to the vet, it could be nothing, just upset tummy, you should let him eat some grass if he wants to. This is something they do if they have an upset tummy, sometimes it helps them. If he keeps throwing up though, I would get him in. Hope this helps, good luck.