Are the smoothies milk-based? If so, maybe try some that aren't - drs told us that milk products would contribute to mucositus. As far as nausea from radiation, our RO said the same exact thing, but I still have to wonder if the radiation doesn't cause nausea, maybe not from the radiation itself, but the mucous it creates, as Gary stated. Even when my husband's nausea problem is calmed down, seems as if he always gets sick in the morning regardless, and we are thinking it is because he is not getting rid of the mucous as frequently, even though he wakes up numerous times to expel it, and subsequently has a lot in his stomach in the morning.
Hope it goes away soon - good luck!
Michele