Why is this happening to my orchid?

[FlowerGirl72410]

My orchid was beautiful until about a week ago and than the blooms started wilting and falling off one by one, and the slick from a certain point is brown the rest of it is green. I've done everything I know to do for this orchid. I've spent almost $100 on it to keep it happy and it is still dying. This is my second orchid, my first my grandmother accidently killed and now I'm on my second and this one is a phalaenopsis. I repotted it after buying it and it was beautiful for about a month or so than it started this. I've bought it special dirt that promises to keep the water at just the right amount, two bags or orchid mulch, a big pot, orchid food, I water it about once a week and mist the leaves and blooms daily as instructed on the tag it came with. I gets plenty of sunlight it's in a room with two windows so it gets light. I keep my house at 72 all the time. I don't really know why this is happening? Is it natural? If it's natural will my orchid ever bloom again? If it's not natural all i have to say is these orchid are not as easy to take care of as the tag says because to me this is turning out to be costly and hard to do.

Heres a photo of it when I first got it and it looked like this up until about a week ago.


Here is what it looks like now, the flash made the photo suck but you can tell whats left of the blooms is wilting slowly one by one.


Here you can see how my stem looks