Post Kidney Infection, Bowel Infection and Viral Infection

At the beginning of September I was diagnosed with a Kidney Infection for which I was given a course of antibiotics for 5 days, my symptoms persisted and worstened and after going back to dr I was diagnosed with a bowel infection and given further antibiotics for 7 days, symptoms persised and I was given further antibiotics for another 7 days.  I was also diagnosed with a viral infection at this point.  My temperature at its worst was 104.  I have now been off the antibiotics for a week but feel so tired.  I have returned to work on a phased entry for only 3 hours a day but come home and sleep for 2 to 3 hours.  I feel exhausted, I now have back pain and a small amount of abdominal pain and am so scared it is all coming back - how long will I feel this tired?