I am 19 years old and I have Arnold Chiari Malformation. Your Symptoms are a lot like the ones I had except I didn't throw up I am Just Nauseous all the time. They prescribed me Phenergan for it. I Found the Chiari at 16. I waited a year to have my first decompression surgery and it helped my daily headaches. But since I waited so long to have mmy surgery my other symptoms didn't improve after the surgery. Such as nausea, balance, coordination, dizziness, etc...Im Actually getting worse and Im looking at a spinal fusion next month for my balance and coordination. From this condition I have developed ataxia, sleep apnea, neuropathy, depression, POTS, cervical dystonia. My advice to u is to have an mri of the brain with contrast to see if they find chiari. The sooner u figure this out the better outcome u will have.