This sounds like transplant shock on your mockorange. Have you checked the soil in the root zone to see how wet or dry it is? Normally a container-grown shrub would need watering every other day at first until its roots expand into the surrounding soil, but if there has been a lot of rain, it may be too wet. On the other hand, if it had roots confined in a tight ball in the pot, it may be drying out daily. The only way to know for sure is to check the soil in the area of the original root ball.