The same problem I had earlier with my Panasonic Lumix DMC FX30. At that time I recognized the vacuum cleaner, the dust was out of the lens system and the photo worked perfectly again.
When DMC SZ7 I can not suck the dust out.
The photo I have ever plugged in a camera bag and handled with care.
Now I have to look for a professional ....
Addendum 10.18.2014:
Dust removal was offered for 100 ... 150, - Euro.
I bought a new, more powerful camera from another manufacturer.
Met with the same dust problem even other Panasonic owners.
Too bad, otherwise the camera was good. But I buy no more determined Panasonic.