Kidney problems?

Last week I posted that our 5 month old Charlie had diahrrea, which was accompanied by mucus and blood at times.  He has been on an antibiotic and a bland diet since.  His stools are finally starting to harden, as of today.  We took him to the vet on Tuesday because the stools were still like a pudding consistancy.  They ran blood tests to rule out any major issues.  When the tests came back on Wednesday, the doc said that he had mild anemia, and high phosphorus levels which may be due to some sort of kidney problems.  He also indicated that Charlie's instestines were slightly inflamed.  The vet ask us to bring in a urine sample.  Today when we spoke with him he said he had to consult with the internal medicine doctor and would get back with us as soon as possible.  Charlie has also been sleeping a lot, and hasn't wanted anything to do with drinking water.  We've had to give him ice cubes to get him to consume water.  With in the last couple of days, he has been leaving pee trails on the floor, and doesn't seem to realize he is doing this.  He is trained to ring a bell on the door when he needs to go out and hasn't had any accidents in almost 3 months.  Any ideas as to what might be going on?