so the symptoms of tb include
Nausea / weakness / fatigue
Rapid weight loss
Fever
Night sweats
Cough
Chest pain
Haemoptysis
but can someone explain to me- why these symptoms arise? what causes them- they are all signs of tb but why do they appear?
also how do doctors differentiate between another disease and TB?
lastly does anyone know what the human body does to get rid of tuberculosis disease?
Thanks in advance 
See reference materials on the symptoms of tuberculosis
the symptoms come on because the tb. germs are foreign to your body and you are trying to fight them off and also it is causing damage & irritation to the lungs.
a chest x-ray is the 100% way to tell for sure and it rules out other diseases as well.
a very strict medication regemin that takes months to complete (like 6 months, i think) but it has to be redone from the beginning and lowers your chances of cure if the treatment in messed up in any way (like missing a dose) it also can cause treatment to last longer than 6 months too.