My period is 2 months late and I took 4 pregnancy tests, all which came up negative. But lately I've been having lower back pain and pain on my sides. I'm nervous as to what this could be. Any suggestions?

It would be wise to see your doctor since you are getting negative pregnancy results. There can be other possible causes as well that would need to be checked.

I have a GYN appointment this Monday so hopefully I can get some answers. It's freaking me out because the longest I've been late has been a month but I've never experienced pain like this before. Thanks for the advice though.

Go to a doctor and get tested it's the only way you can be sure that your not pregnant. Panicking and stress can delay your period so when you stress more and more it might be messing up your hormonal flow and making you late. Its amazing how much our head can screw us up . Stop worrying and go see a doctor :)