Feeling spinning sensation from 2 months

Hi, My husband is feeling spinning sensation from two months. It was very less before but now it has increased a lot. If he is going out and has to stand still for 5 mins, he feels he will fall down, he feels diziness plus he feels he will puke but he wont puke. Its just a feeling and now its happening continously from 10 days. His Bp is normal plus his haemoglobin is 14.5. And all the other tests are normal. He went to neurologist and he said to do the vitamin D and b12 tests. Vitamin D was normal but b12 was on lower side 229. He is having vitamin capsule but no changes in the health. He is not able to concentrate also because of the head spin issue and he feels that to focus on a particular thing is getting difficult for him.We went to ENT , he said there is no infection in the ear. He has one issue that he cannot sleep properly in the night because he sees lot of dreams and feels his brain is active always and its happening from past six months. Could you please suggest?