I didn't want to make a new post about this, but I was using Java 8 for the longest time until I just updated to 1.8.0_20 and now I'm incapable of opening Forge with any version.
I found this, https://github.com/MultiMC/MultiMC5/issues/198 which explains a lot. I'm not sure if this has been posted on in another topic, if so please forward me. The only fix I found was to install Java 7, which I'd prefer not to do...
Thanks