High Platelet count

I'm 39 years old and over weight, 3-4 months ago I was sent to an ear, nose and throat specialist because I have serious allergies. My nasal cavity is crooked and that causes all my sinus infection. The specialist also told me that I have arthritis in my left jaw.  I went to the doctor yesterday because Saturday I started experiencing major pain from the lower left side of my back coming around to the front of my stomach.  I was having trouble with BM and I felt gassy but nothing was coming out.  By Sunday night the pain was all the way up the left side of my back.  The doctor gave me a quick blood test and urine test.  He said my urine showed I have an infection and the pain I was feeling was from my left kidney.  I mentioned that I have had heartburn for the past few months like everyday all day. He asked if I've ever had my gall bladder checked and I told him 2 years ago my other doctor sent me and everything was ok, so she said I was probably going to start having problems with my gall bladder.  This doctor advised me to double up on my Zantac and he's sending me to have my gall bladder checked again because he thinks the root of my digestive problems is my gall bladder.  He also noticed that my platelet count was 600-something and wants to send me to a blood specialist.  I told him that I've been told before that my platelet count was higher than normal, and was sent to donate but never sent to a blood specialist.  Does infection or inflammation cause high platelet counts?  What can high platelet count indicate?