When my sister was 15 she weigh about 140 or so, she was kinda thick. Out of nowhere she began complaining about her joints hurting, she was tired and sleeping all the time and had really bad fatigue and was losing weight pretty fast. At first we thought nothing of it but when the symptoms persisted is when we took it serious and took her to the doctor. The doctor said she had sickle cell. That didn’t sound right at all so we went to another doctor to get a 2nd opinion and it turned out to actually be leukemia.