Having Severe Body Pain, Mild Fever. Blood And Urine Test Normal. Given Antibiotics And Voltaren. Worrisome

Question: Dear Dr. Grief, I would like to ask a question about my brother. He has had a severe body pain ( especially the joints ) for about a week. Besides that, he has mild to none fever and he sweats a lot. No cough or throat infection or headache sneezing, stuffy noise etc.He does not have any of these. At the hospital they did blood and urine tests and they said they look OK. The only thing that was not OK, the CRP 8 level was higher than it is supposed to be and also the white blood cell count was higher. Doctors concluded that, he has an infection but they dont know where it is originating from. They gave him a wide spectrum antibiotics and voltaren. His pains redued after taking the voltaren and at least he is able to walk down the stairs, which was too painful for him because of his body pain. He started this regimen one day ago. I am so worried. It it OK treating the patient without knowing the source of infection ? What do you think his condition could be ? Do you advice any further tests ect ? I would be very appreciated for any helpful reply, Thank you very much in advance.

His medical history :

he does not drink alcohol but smokes little bit. He did not have any serious medical problems. He has been being treated by paroxetine and propanolol for his anxiety disorder for about 4 years. The only problem he had in the past, he had narrowness in his urethra and for that he had two small surgeries so that his urination wouldnt be painful.His last surgery was 3 years ago. He does fine about that. three weeks ago, he stayed at a hospital as a visitor a whole day while his wife was giving birth to their child and after two weeks of his hospital visit, he started having this body aches. Could it be possible that he got infected at the hospital. He is a proffessor at a college and his working conditions are pretty hygenic.