undiagnosed lump on neck

Hi, my sister, Caitie, would like to know if it is bad that there are two little lumps growing on the left side of her neck. They appear to be attached or growing from the muscle. She discovered the bigger one yesterday, and the smaller one today. We haven't sought professional help because our mother doesn't believe it is dangerous. But Caitie, being a hypochondriac, thinks it is really bad. She doesn't know what to do, and our mother wont schedule a doctors appointment. Please tell me what I should do to help her, or if it is worth worrying about. Thank you.