Damp patch on wall

I have a damp patch which seems to be spreading over my kitchen wall. No running water just damp wall. I have had a recent plumbing problem fixed (which originated in my bathroom and I thought it was the aftermath of that but it seeems not). The wall near my guttering is wet and I think it may have something to do with this. Can anyone give me any ideas and give me a rough idea of how much replacment guttering might cost. Mine is a small terraced (my kitchen is an 'add' on). Thanks. Berni Griffin