My Challenge with Weight

Two years ago I was 107 pounds, 5'3, and healthy, but when Cross Country season came around I realized how out of shape I had become and was determined not to stop running after the end of the season. And I didn't. I ran 20-30 miles a week up until the next season. But I wasn't paying attention because maybe if I had been I wouldn't have ended up where I did. I went out west with my family 5 months after the end of Cross Country, five months into my running. That vacation was the last time I had my menstrual Cycle, it's been a year now. I figured I was because I was a runner, and in reality, yeah it was but I was also because I had lost seven pounds in the last six months. I didn't realize this until I stood on a scale that April, wondering how it had happened. I didn't spend to much time on the question though, for I continued to up my miles as summer vacation came around. When I got my physical for the next Cross Country season in August, I was 98 pounds, my blood pressure was 100/50, and my heart rate was 50 bpm. The woman examining me gave me a look I now recognize as worry, but she said I was good to go. But what came next was even worse. I had signed up for Marching band and Cross Country and didn't realize how little free time I would have, to eat, to relax, and to worry about me. I was running 4-8 miles a day and eating only around 1000-1500 calories a day, which for a growing girl isn't good. When I got my yearly checkup I was astounded by my weight, a whole 94 lbs. My heart rat was 48 bpm, although my blood pressure was higher. My doctor told me to eat more and to come back in one month to see my progress. The next month I was 92 lbs, then she said every week. In two weeks I was 90, and by three I was 89. My heart rate had dipped down to 27 bpm, yes 27, one night, I was constantly cold, dizzy, and weak. By the time I was 89 I really worked at it and manage to get to 92 lbs by the time I met with a specialist. She needed to take my blood and see me every week, but I only met her once before she admitted me into the hospital. She said I was suffering from re-feeding syndrome and she would need to monitor me even more just to be safe. It was terrible. For eleven days I stayed there, the alarm going off for the first 4 nights for my heart rate going below 35 bpm and the struggle of being restricted to a bed for the first seven days, only allowed up to go to the bathroom.
I'm better now, almost 3 months later and I'm at 98 pounds, running again, and feel much better. Just pay attention to your health folks so it doesn't get the best of you. Thanks