I get Temporary loss of side vision for the last few months. Why?

In the last three months for at least four times, my side vision was affected and nothing was visible in the side while the straight/front vision was normal. After some rest, the side vision regained to normal but severe headache lasted for at least half an hour after regaining vision. When i visited doctor, she said, my optic nerve was normal. my doubt was if it is glaucoma, whether the side vision would be temporarily affected and regained in few minutes??