I suggest cutting your losses and getting something like a .270 Win .280 Rem, 7mm-08, .308.
If it hurts that bad (5 shots and have to stop) I doubt that you will ever be able to shoot it well.
The cartridges I listed are easily good to 300 yards on even big animals like elk and moose and quite a bit farther on deer and antelope. They kill just as effectively at these distances with out the recoil associated with the 7mm magnum.
Having said that the limbsaver recoil pad helps a lot. I have a 338RUM that hurt with the factory HS Precision recoil pad. I installed a Limbsaver and on that rifle and can shoot all day if I want to.
You can also add weight to the rifle.