Hi Welcome to health care magic. Your husband will need to continue on immunosuppressant drugs which support the function of the transplanted lung, off course these drugs are well known to cause nausea and loss of taste, at times even bitter taste in the mouth. There are lots of drugs with improve sense of taste and decrease nausea. I think your physician will be apt enough to give him a trial of them. The more alarming problem that I can see with him is that he is drowsy. The drowsiness in this group of patients can be a side effect of the immunosuppressants as such or there can be some infection like bacterial or viral or fungal infection affecting him in his brain. He should get a clinical examination by a neurologist to rule out any significant neurological infection and also he should get examined by a physician to rule out the infections at any other site or to detect some other causes of altered sensorium like abnormalities of electrolytes and side effects of some other drugs. I hope the advice will be helpful for you.