Be careful - my father had the same problem for 6 to 8 months and saw a lot of doctors who just gave him medicine. After a lot of tests (X ray, tissue test and .....), the doctor finally suspected that my father might have lung cancer. Therefore, in order to speed up the process, I brought my father to have a test in private hospital and it was confirmed as lung cancer stage IIIB. Does your mother loss a lot of weight? If yes, you have to be careful and ask the doctor about cancer.