I would really recommend taking a serious look at the scope as your case sounds like a classic "scope went south" scenario. You say your groups are erratic which would be a good indication the erector spring (the spring that presses the erector tube firmly against the elevation and windage turret contact points inside the scope body) broke or came loose and is allowing your erector tube to dance around inside the main tube with the recoil of each shot.

This photo illustrates the erector spring assembly in a Swarovski rifle scope, but the principle is the same in most every scope on the market as they all use a spring of some type to support the erector tube. The erector spring is highlighted in red.