Since you've been to a doctor and s/he said it was a gastro bug, then it may well be one but it should start to clear up in a few days . . . now, if it does not, and I am just speaking from my own experience and not as a med professional, you may be having what I have had which is Irritable Bowel Syndrome . . .because the brain and the gastrointestinal track use the same nerve system, etc. (my doc explained it to me, but I don't remember the technical details), someone like myself, and perhaps you, when we are suffering from anxiety (and it may be even unknown to us), we can develop a GI tract symptomology . . . called IBS . . . .for me, when I had an IBS episode, it feels like my gut is moving all over the place (and, apparently it is), I want to vomit, I feel sweaty, etc. etc. . . . .\
Now, my question would probably be is if there is some stress (new or recurring) that seems to be taking a prominent stage in your life right now . . .this may be causing your GI issues . . . .if, however, the symptoms clear up in the next 3-4 days, it might be a gastro bug; if not, then you may want to consider asking for a referral to a GI specialist who will be able to determine if it is a physical / medical issue such as diverticulosis or if it is a physical / anxiety issue . . . Personally, and it takes time, I had a lot of success with mindfulness techniques . . . .I still get anticipation anxiety (reason why I cannot eat before a presentation) but the GI issues such as the IBS are not as pronounced or as long lasting . . . for example, prior, if I had a presentation on a Thursday, I would feel sick the week before and then the week after; now, I might feel anxious a day or so before the presentation but within 24 hours of the presentation, the feeling has disappeared . . .
So, you are not alone . . . I know perhaps 4 or 5 other people who have the same reaction but the strategy was to identify the cause of the anxiety and dealing with the cause usually helped to resolve the GI issues . . . sorry I could not be of more help . . . if you can, let us know how you are doing, take care, kc