By the way, your mom is stupid. Cold viruses don't do that.
Yes they do.
The virus passed along from the throat to the eustachian tube and it's now causing his middle ear to fill with infected liquid.
You're going to develop tinnitus or a really nasty ear infection unless you get it checked out.
If you're wondering how I know this, the middle ear infection is causing the vestibular system in his ear to stop working correctly, which is responsible for his vertigo.