unraveling stitches

After I had completed a shawl, I noticed that a hole was forming in the middle of the shawl!

I realized that I must have trimmed too much of the excess yarn where two skeins met. I was able to tie the loose ends but I'm missing a few stitches. I was using a double stitch.

I've only been crocheting for about a year.

How do I fix this hole?