Another thing that may be tried is if you can borrow another lens then try.
Also do the following:
If you have a Tripod Clace camera in it and with Af assist on hold shutter button halfway down and allow lens to focus on something.
Now while your eye is against the eye cup adjust the diopter adjustment beside the eye cup (the little volume control type adjustment is a PIA to adjust unless you have very slim hands. If you can see the focus on the eleven tick marks for focus point. Adjust them until they are the sharpest you can get them. These are the faintest marks and I have difficulty seeing. On my old 3000 it used a 9 point system and the tick marks were really Dark you could definitely get the diopter adjustment right) adjust until you get picture and tick marks the most in focus possible.