Advice needed

[HakunaMutataa]

We got new sofas around December time. Initially we flipped the cushions weekly but we have been lax recently and it has maybe been a month or more since we flipped them.

Flipped them today and noticed that the cushions themselves all smell really foisty. The foam inside the cushions doesn't smell and isn't mouldy. The part of the sofa the cushions sit on also smell foisty. There's no sign of mould or anything anywhere else in the room.

What could be causing this abs how can I get rid of this horrible smell?

Do you have high levels of condensation in your house? I live in a period property and upstairs is pretty dry but downstairs is prone to general dampness so I have become a bit obsessive about airing the downstairs rooms and also using a dehumidifier on a daily basis.

Thanks for the reply. We do get some condensation on the windows on a morning, just between when it starts to get cold and before we put the heating on. I wouldn't say excessive though and the house is showing no signs of dampness anywhere else. Could this be the cause?