My father, aged 68, some 6 months back was diagnosed for Spine TB and he started on AKT4 for 2 months, AKT3 for the next month but had to stop due to vision loss and following 3 months was taking Rifampicin and Isoniazid. His vision is almost back with some eye power complaint but since last month he is complaining about arm pain near the shoulder joint. There is a slight muscular swelling possibly which we feel there. I read that Isoniazid can cause these side effects. What could be the reason and if it needs any urgent attention to treatment? FYI. He is taking 40 mg of pyridoxine, his blood work shows mild thrombocytopenia, haemoglobin = 11.4, platelet count=106, ESR has come down to 60, CRP has come down from 67 to 8.4. His back is almost gone.