For almost a week now I've been feeling extremely tired even though I've been getting enough sleep, I also have a headache that won't go away. Nausea, constipation, blood in stool, dizzy, sensitive to sunlight, and the strangest thing is I've been having hot flashes to the point where I feel like I'm going to faint. I thought I might be pregnant but the test came out negative. Can someone tell me what may be the problem?