Haemoglobin loss suddenly. A problem!

My father in law have a problem regarding sudden loss of haemoglobin in 2013 which was caused by malnutrition and vitamin deficiency. at that time the bone marrow test was done which shows normal report and he was cured.But recently for 5-6 months ,again his haemoglobin decrease to 6.8-7.1 and he lossed weight from 84kg to 70 kg. (height 5.10ft ). he used to have panmasala but know he only smoke about 3-4 cigarettes per day. He was going through insomnia and mouth ulcer. Does there any risk of cancer? or what kind of disease he have? He had normal bone marrow reports in 2013. I am very much worried for him and afraid of cancer. If you kindly tell me that if there was any risk of cancer or not? and also Please give me clinical suggestion regarding his treatment. please reply.