Kevin17, try not to be scared. The tinnitus has come due to something....could it be that you had a viral infection?
You mention that it may have been exposed to loud noise...what was that noise? The louder the noise and the longer the time that you were exposed to it, the more likely you are to develop tinnitus.
Sinusitis (often related to allergies) can cause tinnitus. I am assuming that the nasal spray was steroid based?
Have you had any other drugs...either prescribed or recreational that may have caused the problem?
The fact that you have normal hearing is good. It will be helpful if it is possible to determine the cause of the tinnitus, as finding the cause may suggest something that can be done.
The general rule of thumb (and it's oh-so-often wrong!) is that tinnitus of under 6 months duration may go away.
If it does not, things WILL improve.
You may need to seek out other opinions from doctors who have an interest in tinnitus (many don't!).
Tinnitus cannot harm you.
Fungus.