I HAVE RECENTLY HAD AN ABDOMINAL ULTRA SOUND AS PART

I HAVE RECENTLY HAD AN ABDOMINAL ULTRA SOUND AS PART OF MY ANNUAL CHECK UP. EVERYTHING CAME UP NORMAL WITH THE EXCEPTION OF MY KIDNEY (1 KIDNEY) FILTRATION RATE BEING SLIGHTLY LOWER. SUDDENLY, MY STOOL COLOUR CHANGED TO A LIGHT YELLOW, WHICH HAS BEEN CONSISTENT FOR 3 - 4 DAYS. IS THIS CAUSE FOR CONCERN? ACID REFLUX IS ALSO PRESENT. ALSO, THE USUAL PAIN UNDER THE RIBCAGE (CENTRE TO THE LEFT OF THE CHEST) IS SHARPER. I AM AWARE THAT FOODS CAN CHANGE THE STOOL COLOUR BUT IT USUALLY DARKENS IT. NOT TAKING MEDICATIONS WITH THE EXCEPTION OF ANTACIDS AND MULTIVITAMINS WHICH I JUST STARTED RECENTLY. SHOULD I BE WORRIED?