Hi, IMy 86 Yr Old Mother Just Felt Dizzy And

Hi, iMy 86 yr old mother just felt dizzy and she could not catch her breath. There was no pain so she laid down and started to feel better within minutes. She now breathing ok, but she says she hears a booming noise in her head. Not a ringing in her ears, but like a slow bang! She does not hear well at all, and refuses to wear her hearing aids. What's making the noise? Is this serious?