In my experiences with Kratom withdrawal, I did not experience any nausea to speak of. However, I had VERY little appetite. I do not remember eating any large meals at all for the first 3 days, I sort of just picked at snacks every couple hours. From what I have read, this is not a good idea as a healthy appetite is reported to help heal the brain more quickly in a WD situation. I have a buddy that smoked weed several times per day every day for about two years and when he would try to quit, he would become nauseous and in turn had no appetite. It may help to drop one at a time of you're interested in quitting both. Also, everyone is different. Some people have typical withdrawals and some vary wildly. It seems as though with Kratom, the withdrawal is very user specific. Try to take some Dramamine or some other antiemetic next time you try to detox, Dramamine will probably help you sleep as well.
Good Luck. It's only 3-4 days and it's over