try not to worry. could be hairballs, overeating, allergies, worms, etc which are all treatable. feline distemper is the only thing that would be worrisome. is your cat vaccinated? here is a list of other probable causes I pulled up from my endless archives:
Dietary problems include:
sudden change in diet
ingestion of foreign material (garbage, plants, etc)
eating too rapidly
intolerance or allergy to specific foods
Problems with drugs include:
specific reactions to certain drugs
Ingestion of toxins:
Lead, ethylene glycol, cleaning agents, herbicides, fertilizers, heavy metals all specifically result in vomiting.
too little or too much of certain hormones, trace elements, etc.
Disorders of the stomach:
obstruction (foreign body, disease or trauma)
assorted gastric disorders
Disorders of the small intestine:
inflammatory bowel disease
Disorders of the large intestine:
irritable bowel syndrome
gastrinoma of the pancreas
peritonitus (any cause including FIP)
inflammatory liver disease
bile duct obstruction
pyometra (infection of the uterus)
pain, fear, excitement, stress
so its a good thing he's going to the vet. they'll get to the bottom of it.
We don't, but i'm seriously considering it now! 4 years of no problems with our cats, we get him and BAM, we've forked over almost $500 in vet bills not counting this one. He's a bundle of fluffy expensive cuteness! LOLHope things go well for you and little Nacho.
Do you have pet insurance? I have it for my baby and I love it. I use VPI. It's great for times like this.