Window leaking, contractor recommendations?

Today I noticed some water damage in my drywall and noticed that it seems like it's coming from the top window of my family room given that I see some water stains around the corner of the window frame.

Does anyone know who I can call in this situation, and will they or can do they do anything in the middle of winter? Pic of the top window attached. I circled the top part where I see water stains and the direction the water seems to have seeped through. The bottom circle is where it seems to have stopped.