back injury

He guys,

I am doing Sprints(18years);
i have got a light to medium pain at my back, just over the glutes. I had to rest several times, but nothing helpes…

Now a doc found that my creatinin in my blood is too high. The doc says that there could be some problems with the kidney…

They told me to go for supplements.
Does anybody have equal problems??

Found also out, that I get a pain, if i a have troubles…very strange…