Loss of smell, what could it be?

i feel different in one of my nostrils but the other feels fine. in one nostril does not take up much air as the other and this also then affects how i smell things, and it is annoying. also when i lay down , it goes to the other side and feels blocked , like i have a cold in just one nostril. the sides sometimes switches left or right. its annoying and want to sort it out but do not want to bother my doctor just yet