Two years ago I dealt with this same thing and my children and I seemed to pass it around to each other, I became pregnant and it stayed away, and on the 4th of July it returned and I've had this 3 times total counting the 4th's start.
It begins with a horrible taste that I get from an uncontrolled burp. The taste is VERY distinctive and from that I know what is coming with in the next 4 to 6 hours. After a few hours of dread and the horrible taste comes the vomitting. Two years ago I would vomit off and on for a full 24 hours, this time around though the vomitting is only lasting 2-4 hours. Normally the last hour or so of vomitting the diarreah hits, which can last from 2 or 3 bouts to hours of it. At this point I've had it once a week since July 4, but the previous time with this it came about once a month from October '08-April '09. We have moved from an apartment to a house and I honestly thought it was something in the apartment that was possibly causing it. I "thought" that we had a horrible virus and even thought I continued to clean everything that it was just trapped, but we've moved, my husband and I have steam cleaned our furniture, we do not use toxic chemicals (all safe and natural cleaning supplies). Thankfully my children have not been sick with this so far, and my nursing newborn has no signs (thank the LORD for natural antibodies in breastmilk).
I am frustrated and tired of this. I think since I had a year of reprieve it's not considered chronic. I have no went to the dr yet, but am at the point that I'm calling Monday morning when our clinic opens and will be getting an apt. I'd love to go in with some thoughts and if anyone else has dealt with this I'd like to hear from you.