Why does Yahoo think email from me is SPAM??

Recently the Spam filter on my yahoo account has gone nuts in false positives. On any given day, I might receive a number of notifications from Facebook and some news feeds - and now about 50% of them are ending up in the Spam folder. I keep clicking "not spam" - and verifying the address is in my Contacts list but it keeps happening. The killer is when I send email to myself from my yahoo account - it ALSO ends up in SPAM!! I have no filters - what's wrong here and how can I make it stop??? Thanks