phalaenopsis: wilting flowers and brown spots

[hrothgar]

So, I've been trying to get my Phal to re-flower again for the last two years, finally got results in January and saw my first bloom in mid February. Everything was going great until today when I spotted a wilting flower. The last bloom on the spike opened yesterday, and while I understand good things come to an end, it just seems too soon. Also, there are some brown/black spots forming on the inside of four out of six of the flowers. A photo is attached, the wilter is on the right, and the spots in question are visible.

I water once every 7 to 10 days by dunking and lightly mist the roots once or twice a day with a spray bottle. I should also mention things have been very warm but we started a cold snap two days ago, which has effected the temperature in the room.

So my questions: Does anyone know whats going on? And what can I do to fix it?