When my daughter was younger, throwing up was a sign of strep for her (weird, huh?). Apparently, the strep caused her lymph nodes to swell enough to irritate her stomach. Now, mind you, the glands in her neck were never swollen and although she sometimes complained of a sore throat, there were other times when her throat didn't bother her. My sister's son was the same way. Three weekends is a long time for strep to go undiagnosed, but I guess you never know. Also, the same daughter used to throw up if her sinuses or throat were too mucus coated, either from a cold or from allergies.
You've received some good advice from other posters. Maybe just a quick call to your doctor's office would be good. Good luck!