Refrain from touching the lump, it may cause irritation. While waiting for your vet, try to relax and comfort your dog, gently put gauze over one of his ear (make sure it's not too tight, just loose enough to allow air cycle to flow freely). Prevent him from doing strenuous activities such as running inside the house. Please keep me updated.
Welcome to the forum...I don't think there is anything you can do on your own....What your describing could be a few different things.....Any lump, bump has to be evaluated by a Vet.....SOme things are very dangerous & others are not...There is no way to tell without an examination....
Since it's so large & causing pain, I would have him seen tomorrow if possible....Please let us know what you find out......Karla