Still can't find what's wrong with me. ive been having yellow tongue, joint pain, weight loss of 4kg, fatigue, lump feeling in throat and headaches.

See a doctor: For these types of symptoms, you need to have a proper diagnosis. In fact, diagnosis means 'through knowledge'...Once the cause is known, then you can get the right treatment. There are various infectious and inflammatory diseases that could cause these symptoms, and I would NOT wait much longer to get diagnosed. Call your primary doctor today to get back on the road to health.