Am I the only one experiencing these symptoms?

I am about six weeks pregnant and feel pretty icky! I have two children already and had a miscarriage about eighteen months ago. I wake up each day feeling anxious, nauseas, and zapped of all energy. My heart feels racey and I feel kind of clammy most of the time. I have night sweats almost every night. These symptoms are nothing like what I experienced with my first two pregnancies, but are similar to those I felt prior to miscarrying my third pregnancy. I suppose this is what frightens me. Is anyone else feeling this way? Are these signs that the pregnancy is not healthy or viable? I try not to linger on the anxiety, as I know this would be unhealthy to my unborn child. Can anyone ease my mind?