Im not an optomitrist and ive never played one on TV but, have you had your eyes checked recently? sounds more like maybe eye fatigue.
when your teed up on a deer your not focussing on the crosshairs, a paper has no qualities that hold your eyes attention
do you have one eye or both eyes open while shooting? (My shooting improved almost immediately when i used my open eye to look through the scope
)
i find it easier now to leave both open, less eye strain
do you look through the scope for long periods before actually shooting maybe a 'pirate' eye patch would help.
what breed of scope?
did you focus the crosshairs before shooting?