What Causes Pain In Lower Back And Frequent Urge To Defecate?

I started feeling discomfort about a week ago. I had a dull pain in lower back and quite sore on the right side. The right side does not seem to playing up now but the lower back I still causing discomfort. I have a constant urge to go for a bowel movement, which includes once I get there it happens every other time. It s uncomfortable to sit, like it s in my rectum and under my tail bone. I feel generally off and a little shaky. As the day progresses I feel worse and have had a bit of a fever later in the day. I don t have any blood present, nor does the stool or urine smell bad. It doesn t actually hurt to go to the toilet. I am having to sleep on my side or stomach to get any relief.