Extreme fatigue and loss of appetite started about 2-3 weeks ago, now random nausea throughout the day starting a week ago? cause?

Many possibilities: Your symptoms are too vague to adequately trim down large number of possible causes. Drug side effects, pregnancy, viral syndrome, etc can cause your complaints. Go see your family doc for further evaluation.

3WeeksIsLongEnough: Could write a book about this, but focus on whether or not you are pregnant,have mononucleosis("mono")or a liver problem(urine dark?poop light-colored?)or anemic (pale?). Well, look, this could go on and on, what I mean is that your doctor should think about all this, which means you need to see him or her.Sooner than later. While waiting for your appointment, if the nausea gets bad try Dramamine (dimenhydrinate)