Hi, may I answer your health queries right now ? Please type your query here... I blacked out the other day and hit my head pretty good the doctors assumed it was dehydration bevuase my pulse was really low and when I stood up it doubled and they gave me an ivy and it helped. However since then I still feeel occasionally nausious and sleep alot but I'm still always tired and have no energy my head and neck haven't stopped hurting since then and I just feel like I have no energy at all and my whole body feels sore