The doctor probably needs to check her out but from someone who was rubbish at school sports I would like to make the following observations.
I was utterly hopeless at sport, limited co-ordination, very slow, a complete no hoper. Always the last on the bench, ridiculed and humiliated in front of everyone else. It's probably why I didn't stay at school and do A'levels or go to university. The day before or morning of games days it got to the point where I used to develop migraines.
When I left school and started work I became quite competitive, became successful, blossomed and generally quite popular. I am well within my bmi at 51, walk a lot, can ride a horse well and swim well. I had a check-up yesterday and the doctor said I was incredibly fit for my age. Many of my school contemporaries who were in the netball team etc., are now overweight, look years older than their age and appear very unfit.
They don't have class positions at school anymore for academic subjects so why the emphasis on competition in sport.
Our ds is exceptionally sporty and has trialled professionally so I don't think I have passed on my views in particular to my children. DD is just like me and under no circumstances would I force her to do sport and I have often asked if she would like to bunk off PE but schools have improved in their approach and although they need to improve further, she has always said, no it's OK, but that hasn't stopped her crying on a pe/sports day at the thought of the others laughing.
I feel very strongly that there are other more beneficial ways to be fit and to exercise rather than organised school sports and I sincerely believe it should not, under any circumstances, be a mandatory part of the curriculum. If children have difficulty with academic subjects, laughing at them wouldn't be allowed at school; how sad that PE teachers, ime, still think it's OK to purposefully humiliate.