I'd say over the last 10 years we have been getting a very strong fish smell in my home which lasts for about 1 minute then completely vanishes. It's stops for a few years completely then resurfaces. You can actually smell it moving about, like from room to room. House has been inspected by professionals a few times as its embarrasing he when people are over but have found nothing. You may be thinking this could be 100 things but the one thing that freaked me out about was when I was in hospital about 3 years ago and I was very ill. I was taking a bath and the exact same overwhelming smell returned for about 30 seconds then vanished again. I don't believe in ghosts but this puzzled me. Any other experiences with strange smells?