Do symptoms change from day to day?

I found out Tuesday that I am pregnant, after 2 years of trying. I had been feeling nauseous and had sore boobs a few days before I tested. Yesterday I felt TERRIBLE, with some intermittent cramping. Today I feel better, which scares me a little. This is our first pregnancy so I don't know how to feel or what to expect. Today I haven't really had any cramping or nausea...I'm just tired with a slight headache. Is this normal? I went in yesterday for blood work and am waiting for my doc to call me back. I go in tomorrow as well for more blood work to check my levels.