He doesn't undterstand

Im quite early in my pregnancy but I have been having severe nausea and food adversions as well as being extremely tired. I work in a very fast-paced, high stress office so when I come home from work I fall asleep very quickly.. My Fiancee has seemingly been supportive but the first weekend he is actually home and i have a day to relax and he continuously nagging me about how i need to do something and be more active so that I will feel better and has made comments that im "milking" it... Im on meds for my nausea and that keeps it to a somewhat bearable level but I still feel ill all the time.. He won't listen when I tell him that going out or being more active -as he puts it, will make me feel better. It is really pissing me off that he thinks and says these things when I am trying my best and I dont see the problem with having 1 lazy day especially when i have been stressed out at work.