Fever and tantrums

During this past month when we were travelling, I was lucky in that both children remained healthy. Right at the end of the trip, both the kids fell sick, one after the other, with V being the first. I am still very paranoid when he falls sick not knowing what to expect. However, this time, his fever was under control - lasted one day and there were no repercussions at all. I would use Tylenol when I felt his fever come back and it would disappear sooner than later and he would be fine. For this I am more than grateful. Also, touch wood, he is inherently healthy and bounced back the next day.
V has been having more than his share of tantrums. I am not sure whether it is because of all the changes and his routine change or because of the fact that he did not like the bananas while travelling and barely ate them - just one seller whose bananas he liked and would eat one a day. The fact is that I think this is an issue and needs to be addressed and I will check to see what the best approach would be. Yelling is obviously not the right way but reasoning during those periods cannot happen because he is in a non-listening mode. Basically, this makes me even more convinced that V needs a really rigid diet and routine and slight deviations can cause problems.