2 thoughts.

1. When my wife's F150 started ticking it turned out to be an exhaust leak at the head on the right bank. 2 new exhaust manifolds later and we were back in business.

2. If your tick started immediately after an oil change it might be the filter that was used. My brother had this happen when after an oil change when he used a Fram filter, he went to a different brand filter and that took care of it. He forgot about the incident and next time he changed oil, he again used a Fram filter with the same ticking sound, so he changed filters again and again that was the end of the problem. Apparently Fram retricts the oil to the point that the engine is starved of oil.