<s>[INST] Hi, my son 4 years old having weight loss from 15 to 13 kg within 3 weeks duration, suddenly he caught into heavy fever for 2 days and sputum also in pure yellowish color. Further, he had lymph nodes on neck(below the ear) in both sides. After that i conducted mantoux test, the test results shoe negative. but still he had weight loss and fever, is there any possible for TB? [/INST] Hello and Welcome to Ask A Doctor service. I have reviewed your query and here is my advice. I am a pediatrician and happy to have a chance to help you. The weight-loss that you describe along with fever and enlarged lymph nodes are signs of a serious illness. He needs medical care IMMEDIATELY. This could be life-threatening! I push you as forcefully as possible to take him to a physician now. Hope I have answered your query. Let me know if I can assist you further. </s>