Thanks to the last 2 replies! Fortunately Oliver doesn't have any of those symptoms and is perfectly fine now. He has been #1 with the litterbox since the first day we brought him home, regardless of the type of litter in there!!
I will look around for gastro food. I was told to pick up urinary food as well. Since I probably cannot afford vet food is there any brands I can find easily (for a good price) that are good for gastrointestinal and urinary tracts that is also not full of garbage ingredients?