Resistance and Inductance of a ceiling fan motor needed to spec snubber
I recommend you use a 1uf (or larger) 150v AC, capacitor across the motor power leads (no resistor needed). This should help suppress the electrical noise but since your problem started about 3 months ago, that tells me that something changed 3 months ago.  Possible changes:
1 - new TV
2 - new cable box
3 - cable box moved and plugged into the same circuit as the fan switch
4 - fan motor grounding disconnected
5 - if fan has internal noise suppression, it went bad