Rachael, it sounds like your aperture is set to a wide aperture (low f-number), allowing lots of light in, but at the expense of a very narrow 'depth-of-field'. This creates a thin slice of focus where anything before or after is blurry.

Let's assume you're 2 feet away from your subject when taking a photo with your 50mm lens. Most common SLR 50mm lenses have the widest aperture (size of the hole that lets light into) of about 1.8. It's what makes the 'nifty-fifty' a great lens - lots of light is good!

I don't know which camera you're using so let's estimate.

Using this online depth of field calculator you'll see that in the above situation your total depth of field is approximately .3ft or 3.6 inches deep. That creates a very narrow area in your shot that will be in focus. Now if you move the aperture setting on your camera to a larger number (smaller hole) your depth of field will increase.

Let's say you bump it up to f4. At 2ft away from your subject your depth of field is now .7ft or 8.4 inches.

The result however, is that your now letting less light into your camera and will need to adjust your shutter speed or ISO to compensate. I'd start with the shutter speed first - letting the camera expose for longer and see what happens.

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This answer does a good job explaining depth of field terminology.

While a bit technical, this article does a good job explaining the correlation between aperture, focal length and distance to your subject.