Minecraft forge stopped working?

Ok so a couple months ago, I wanted to get a wireless redstone mod so I downloaded the 1.7 version of it, forgetting that I had 1.8 forge. When I tried to load up minecraft with the new mod, it just crashed. It is not uncommon for my game to crash once after a new mod, but then it crashed again and again and again. I finally had to resort to re installing forge. Now it still crashes but before it does so, under the Mojang logo, it says loading - constructing mods 1/7. It stays for a few seconds then crashes. Oh and in the bottom right corner, there's an anvil that is being banged on. Does anybody have any idea what this is? What can I do to fix it?