That did indeed fix the problem - thank you so much!
SUMMARY OF FIX:
1. See if you added a border to either the content or the sidebar area. If you extend the width of one by using a border, then you must decrease the width of the other by that amount, or else they will no longer fit next to each other and the sidebar will get pushed down.
2. Depending on your theme (e.g. I'm using a child theme), you may need to put !important in your width adjustment in order for the change to be reflected on your page.
1. Some people have errors in their HTML code, and this is causing the problem (this was not my case, but it may be yours). Check your page code by entering your url at http://validator.w3.org/