Talk to General Physician on Long Lasting FEVER That Happen Every Year In Summers

My mother is suffering from fever since 13th June. It was viral (she sat with someone suffering from fever). She felt fine on 15th, but got throat infection due to having food outside (cold salad, etc). She has completed antibiotic 'Leflox' course. Her fever in the starting was 100 during day time and 101-101.6 from evening till morning. Since last two days it has fallen to 99.4-99.6. She is feeling extreme weakness, unable to carry out any routine work. Currently she is taking 2 panadols thrice a day.

Main issue: She gets fever every year in summers (extreme heat/ heat wave period) or if she travels long distance during summers. For the last 3-4 years we have witnessed same kind of fever in which we get all the tests done and no infection is found. She is diabetic and hypertension patient. Last month she had extreme back pain that was felt in her lower back and it ran through hips. The back pain is not present now.

Kindly assist in understanding the problem.