Weird smell in kitchen

Hi We recently moved few days back to a house (on let) I started getting some weird smell in the kitchen and living room (living room is connected to kitchen and then small conservatory but has a door connected with kitchen) smells like some slightly dead rat smell but not exactly. But after googling in the internet it says could be kitchen cupboards which is of wooden. But still we r u unable to get or know what it is. The let agent john shepherd said everything was cleaned and done. we dont know what to do with the smell. been already 2 weeks and smell is still coming, tried room freshner but still no use. Also im getting continuously sneezes and cold due to that smell i feel. I have a new born and toddler that is why im worried. please advise or suggest what can be done thanks very much in advance xx