A stomach virus or flu that other people get too (sometimes its hard to tell which I have)almost always lingers longer for me, sometimes for a few weeks. I find that I become very food intolerant at those times, it helps to eat smaller meals more frequently, but sometimes the D just seems to get the better. I cant really say that I do anything special to get it to go away, it just eventually does I guess (probably just my IBS flareup calms down), it can be very discouraging in the meantime. The regular flu-influenza-fever, nausea, cough, wiped out feeling, etc. also seems to have a stomach component for me, I just got over a flu-like illness, no fever, yes-sore throat, tons of post nasal drip, nausea, altered BM's (more than what is Normal for me)and even this type kicked up my IBS but thankfully not real bad. Yup you definately have a motility problem, so do I, but you already knew that
I hope you start to feel better soon, do give probiotics a shot, my IBS C and D flared (the D) after antibiotics and probiotics/acidopholas in particular really helped me turn the corner towards getting better. Hope this helps
------------------Nancy