Jeff, is your tree out or have you recently brought it indoors? Sometimes when a tree is brought in the house, especially if not first acclimated, leaves will drop. If this is the case, in time the leaf drop should stop.

What size pot is your tree in? The number of days between watering doesn't really say much. In ohter words, that could be too often or too little depending on sun, temperature, humidity, size of pot and soil.
The cooler the temps the longer soil takes to dry. If kept warm/hot then soil dries faster.
One other thing to check for is bugs..I may be jumping the gun but it never hurts to check..Toni