If you are seriously ill during the night, you will make it quite obvious to him, I am sure. Nausea isn't a serious medical situation, and you seem to know how to avert the subsequent panic attack.
You felt guilty about disturbing him - maybe he felt that you were coping well, and once you were in the other room that he would be disturbing you if he followed you. Perhaps also he wondered why you were staying away from him after asking him to keep you company?
Do you take these nauseous turns often? If you find them worrying and long for company and support, it would be a good idea to sleep in the same room all the time, then he would be on hand all the time.