there are very long list for PUO i.e pyrexia of unknown origin and your son was diagnosed of latent tuberculosis and on treatment for 2 months. kindly continue the treatment for 6months to one year. wat you can do is
first- take senior physcian expert in the infectious diesease opinion
second - abdominal laporatomy - but this is less common now a days becoz of nnewer technique
third- to observe on 1 or 2 months and then again taking proper history and physical examination proceed with further investigations to rediagnose.
at last- PUO for one year or more you can think of infections like
osteomyelitis , malaria, trpanosomiasis and whipple diesease.neoplasms like - lymphoma, adenocarcinoma of colon.
connective tissue disorder like arteritis,
temporal arteritis, poly arteritis, takayasu
erythema multiforme.miscellaneous like hyperlipedemia, fabry diesease,
periodic fever, thermoreulatory disorder.cyclic neutropenia. at last factious illness.
i feel your doctor is in third stage of following your son , so kindly consult him again to re- evaluate with proper history and physical examinations.
thank you