What Causes Pressure In Bladder After Urinating After Eating Dried Cranberries?

I am a 43 year old male and I have never had an issue like this.This past weekend I came down with a fever. It broke a couple a days ago. Yester day I ate a small amout of dried cranberries. Since last night, I felt like I had pressure on my bladder even after urinating. Since this afternoon, I now see redish and brown particles in my urine. I have been consuming mostly water and tea without sugar since the start of fever. Please advise. Thanks.