Could Gold Coin Grass cause Kidney stress?

I have been taking the GCG for almost three weeks now, with what I think are good results. Last night I started to have problems urinating (feeling like I had to go right after I went, trouble going even though I felt like I had to go, and pain in my right lower back area). I had kidney infections pretty frequently in college, so I thought that was what it was. I went to the doctor this morning and he said there was no sign of infection. What else could be going on and could the GCG not be agreeing with my system?