I looked up salmonella on the internet and the symptoms you have described for your husband sound more like lactose intolerance. Salmonella symptoms are somewhat similar, but include nausea, vomiting and diarrhea, stomach cramps and fever. Thus, I suspect something else is triggering it. Yes, your husband can spread it you even if you don't eat the contaminated food.
This info I got from my government on the public health website here:
Lactose intolerance symptoms include: abdominal bloating, gas, nausea and diarrhea.
I highly recommend visiting your doctor to get a proper diagnoses, but in the meantime get your husband to stop eating the nesquick for at least a week and see if his symptoms don't improve. I would also suggest staying away from all dairy products for a week too and see how he feels. Then re-introduce dairy again and see how he feels. What he is experiencing sounds like what I went through before I knew I could not digest dairy, and milk was the worst.
Hope this helps and I hope you and your hubby feel better.