Do you pronate your feet or engage in ankleing? Probably no orthotic if your ankle is fine or foot arch doesn't collapse.

Also your saddle may not have been aligned properly such that when you sit on it your hips are not or were not during your training pointing straight forward... switching the saddle may have caused this change. This offset angle made by the hips will be "corrected" by the other joints below the hip, such as knees or ankle. So, upping the milage may have proved the tipping point for a muscular imbalance. Double check your pelvis position.