I you have/had candida you will almost certainly have some kind of glucose problem and the chanca piedra could be compounding the glucose problem.
If you have a glucose tolerance check the doctor may interpret the result incorrectly because they are unlikely to be aware of the influence the candida is having upon your glucose levels, and they may diagnose something that isnt infact the problem, that only applies if our assumption that candida is the problem causing glucose levels to be low.
However atleast you will know if you have low glucose levels and that chanca piedra will lower these levels further, potentially being the reason for this herb making you tired.