The game crashed whilst initializing game Error: java.lang.OutOfMemoryError: Java heap space

This started happening this afternoon after running my CCleaner application, but the cleaning did not delete any files in Minecraft, so I don't believe that it was the cause. I have not downloaded any new resource packs or anything recently, so I'm unsure what is causing this error. I have also tried reinstalling Minecraft from scratch, but to no avail. Attached is my most recent crash report. Any help would be greatly appreciated - thank you!