Have Suffocation, Heat And Breathlessness. Have Diabetics. Diagnosed It Could Be Iron Deficiency. What To Do Now?

hello,
my dad is 69. he has been having problem of suffocation, heat and feeling of less air to breath...some what stuffiness in air. recently he got his routine blood tests done and everything is normal except blood sugar. for the very first time his p.p came out about 300. when he consulted his doctor, he prescribed medicine for sugar. he is also a blood pressure patient and takes b.p. medicine. but, here problem is not his blood sugar or b.p....he is some what scared of that suffocation and stuffiness which he goes through during unexplained conditions like in train(though AC is on), in high temperature weather, at home etc
his doctor was not concerned about this problem. he said it was nothing and suggested to apply something like vix or balm kind of thing on nose.

my dad, once spoke to his friend who practices Homeopathy by his own interest. he said it might be due to less Iron in blood which causes Iron deficiency anemia resulting in to such kind of problem.

few days back he had to cut short his journey because he was feeling the same heat problem in train while others were sleeping quietly. although this time he didn't feel like suffocation or less oxygen in air but he couldn't gather courage to travel more after that journey.

please suggest doctor that what needs to be done.