First of all a loud THWACK was you first indication of something wrong from the onset.

Sounds to me like, at best, a shoulder blade hit. What poundage bow ya shooting?

Now you owe it to the deer to put in the time. A large tract of land seems unsearchable, you have to break it down into small sections and search each thoroughly, before moving on to the next small area.

I'm sure if you hit it Weds..that the deer is wasted. look for crows or vultures over an area..it may bring at least a closing on this saga.