Hello, and thank you for contacting Ask Extension about your oak tree. You were wise to call in a tree service to prune your tree after the ice storm. I doubt that the storm is the reason for the drooping now, however.

We have had an exceptionally dry spring, with April being the driest on record. Your tree is probably under-hydrated. 

The majority of feeder roots (those that take up water and nutrients from the soil) are in the top 12 inches of soil and extend as much as 1 1/2 times past the canopy diameter of the tree. Water should be applied in this area. This article will help you determine how much water needs to be applied:
https://extension.umn.edu/planting-and-growing-guides/watering-established-trees-and-shrubs#when-to-water-trees-and-shrubs-1261760

Do not be tempted to fertilize your tree at this time. Plants under stress (such as drought) are only further stressed by fertilization. Adding an inch of finished compost and/or 3 inches of woodchip mulch would help the soil to hold moisture. Be sure to keep the mulch several inches away from the trunk.

If you see other signs of a problem or have other questions, please write again.