I m a 19-year-old female. The last few days I ve been very fatigued and walking even a small distance, like, from my bed to my desk is making my heart race. I could barely lift my arms to wash my hair in the shower. It comes and goes. I also just got my period for the first time in about six months. So I also have pretty unpleasant cramps right now. I suspect the hiatus was due to a lot of stress. Also, I ve been super thirsty and have to pee all the time, really bad. All of this is very new though. Last week I was feeling perfectly fine and exercising daily without a problem. Also, I m within a healthy weight-range and aside from having pneumonia a few times I ve never had a serious health issue.