Hello Sir,I Am 5.10 Height And 72 Kg Weight.past Some

Hello sir,I am 5.10 height and 72 kg weight.past some months I didn't had proper food on time and then used to sleep very late.and I felt stomach upset and little bit pain not in a permenant place.doctor told me this is because of acidity and he was homeopathic doctor.now my problem is I am doing my exercises and gym regularly and having enough calories but weight is not gaining.but weight loosing 500 grms to 700 grams if I reduce calory even a day.and after 5 minuits of my meal stomach seems very lean and not getting stomach full feel during meal.and mouth also feels dry.kindly need your advice.is this because of acidity or any other stomach virus.sometimes I used to had food from outside.and I suspect this because of parasite.need your advice