If it is in ordinary potting soil, that could be the issue right there.

Unlike terrestrial plants, orchids do much of their respiratory gas exchange through their roots, rather than through their leaves. As Geoff said, most often, orchids are potted in a bark mix, coconut husk, sphagnum moss, and the like, which remain open and airy to allow the roots to "breathe" while remaining moist.

What is likely happening is the roots are suffocating and dying, leading to the blossom and leaf loss. I'd repot that right away.