My 4th pregnancy and the morning/afternoon/evening sickness finally went away around the 17th week or so. My OB kept saying that nausea is a good sign that your preggie hormones are up to snuff (if that's any consolation?).
I never actually vomited, but there were times when I really wish that I could have (just to feel better). Mine came without warning and was particularly worse at dinner time (even moreso, the later that we ate). It made sense that nausea increased on an empty stomach so I'd have to agree that it helps to eat more frequent, smaller meals.
For me, ginger ale seemed to help, keeping the starches down (ginger snap cookies, saltines, pretzels, etc.). I was desperate for it to go away and also tried the motion-sickness wristbands (elastic bands with a small plastic button that puts pressure on your wrist/forearm). They seemed to help a bit in the day, but I couldn't wear them 24/7.
Hopefully, your morning sickness will subside shortly :)
P.S. One of the prescription prenates that I took during my second pregnancy seemed to upset my stomach. I ended up switching to a "Natures Source" prenatal vitamin from the local health food store. I have taken this for the last 3 pregnancies.
P.S.S. I know that if your sickness is really bothersome, the Dr. can prescribe a medication to ease symptoms. I'm not real keen on taking medicine during a pregnancy, but if you can't keep food down it might be something to think about.