jaundice has many causes, the most common of which is hepatitis, did u suffer from that? did u take any medications for that?
u have to stop eating from outside, eat whatever u like at home. if u can't help it, then eat from some club such as gymkhana (such clubs have a strict cuisine committee which keeps the hygeinic standards extremely high).. and that too not more than once a week... the other restaurants which have no such control are very unsafe and god forbid, u may suffer from something serious if u continue like this
there is medication to increase ur appetite but i won't recommend it unless the cause is found out. consult a gastroenterologist first so that the cause of decreased appetite is found out. and he too will ask u to stop eating from outside. there are so many online recipes of all sorts of food, u can make everything at home. at ur age, such a low weight is not good ( a height of 5'10" and weight 52kg means that ur basal metobolic index is 16.4, less than 18.5 means that ur underweight)...