And how do I go about fixing it so it doesn't do that anymore?
As the lag is cumulative, you only have a chance to impact your connection. If you see all players appearing to hit you at off angles, then it is your cumulative connection from your computer to the server. Run a PingPlot and see what the path looks like.
With all the damage to the telecommunications infrastructure, from the winter storms, the Internet is a mess with physical lines carrying more than they are capable of causing excess packet loss, huge variances and other anomalies, all bad.
There are a few things one can do to help on the local connection. Make sure you never install from Norton, McAfee, Roxio, Intuit, Apple (iTunes is particularly nasty), or any other applications which are going to phone home, even when they are not running as the main application.
Avoid using a wireless connection, if you can. Quit running background applications. Power cycle your home router, from time to time.