I am hard of hearing person. I just had my hearing test and I lost some more hearing. I was mild to moderate hearing loss. Now, I am moderate to severve hearing loss. I don't know why I am getting this ringing in my ear and then it comes when I hear nothing for few seconds and felt dizzy for few second. Should I ask my audiologist about why I kept getting this no sound in my ears and it comes back to normal? Should I let my audiologist knows about it?

Yes OF COURSE let your audiologist/ENT KNOW about that, it is VERY important. That ringing in your ear is called "tinnitus" and it can get permanent. I had something that looked like an ear infection about one and a half year ago but I didn't go to the doc. I was getting that ringing for like 15 seconds few times a day but after a few weeks it became permanent and I can hear it every time I go to sleep or when its silent. I regret that I didnt see a doc on time.
This can have a million causes and your hearing loss can be connected to it too.

Tell your doc EXACTLY how and when you feel it.

Can I still get this ringing or shutting my hearing when I wear my hearing aids too? I felt few times with my left side since I am wearing hearing aid. I feel more affect in my right side with this sound or ringing my ear.

I called my audiologist about this shutting sound effect my ear. it only effect this sound lost one time a day about everyday when I work around people. She agreed that she thinks I lost more hearing from this problem and she sends me to see ear doctor next week. She will be there when the doctor looks at my ear and see what happen. I hope it not serious. I never lost this much hearing since I am hard of hearing person. I always in the mild to moderate instead of moderate to severe.