Symptoms some days, some days not?

ThisLittleNest • 💏 Married 8/13/2011, 🎀 10/13/2016 🎀, 🤰🏻 10/14/2018 🎀
I've noticed that I'll go days feeling horrible and then all the sudden I will feel energized and no more nausea. My boobs stay sore but the days I have less symptoms my boobs aren't as sore. Does this happen to anyone? Do you know why this happens? I'm 6 weeks and 5 days.