If it feels "squishy" it sounds very like a Lipoma. A fatty tumor, quite harmless. (unless it grows very big or impedes anything it may not need to come off)
BUT...PLEASE don't take my word for it! I am not a vet, and besides, who can diagnose a dog at a distance, without seeing or feeling the tumor??
Try to find a way to get this lump checked as soon as you can. It may cost you but who can put a price on peace of mind?