During the past couple of months, my appetite, which used to be quite voracious, has drastically changed. Lately, just taking 5 bites from a sandwich will fill me up, and if I eat more than that, my stomach begins to churn and do flipflops. I tried to eat a normal diet once and I ended up throwing it all up later that day. I'm very active and before this, I used to maintain a pretty decent diet. Now, just the smell of food makes me so sick to my stomach, and I can't bear to eat it- that's how queasy I feel as of late. As well, I've had so many headaches lately, and my mood's been fluctuating dramatically (happy one moment, sad 5 minutes later, etc. I used to be an easygoing and happy person, but I feel so down and empty lately). When I went to my doctor this past summer, he said that my white blood cell count was low, and my red blood cells are larger than most red blood cells. Would that, accompanied with a concussion a while back, be the cause of this? Do you think it's serious?