emmaBS:
Try to check with both a Dentist and an ENT doctor.
If the odour is caused by tonsil stones, they can be removed.
If it is caused by sinusitis/sinus infection, I am very sure they are going to prescribe antibiotics.
But the problem is antibiotics work for some sinusitis while they don't work for some other sinus infections.
Even in the western world, so many people with sinus infections have not been able to find a solution in the hospitals. It is surprising that many even went through surgeries yet the problem persisted.

This is my advice: if it is tonsils, get them removed.
If it is sinus infection use any drugs they are going to prescribe.
If the drugs work, lucky you.
If the drugs don't work, try quoting me.
I will tell you what I did that solved my sinusitis.

My experience: I had sinus infection in 2014, visited an ENT doctor and the drugs he prescribed worked.

In late 2017, the sinusitis returned. So I visited that same doctor but the drugs he gave me refused to work. I also visited other doctors yet the problem persisted. In fact, the odour increased and I had to start staying indoors.
So I started reading online and found some info on some forums. I tried what I read and it worked miraculously.
Please note that I didn't spend more than 6k on this particular method.
That was after spending about 50k visiting hospitals and doctors.

Summarily:
1. Be sure of the cause of the problem.
2. Let the qualified/trained doctors treat you first.
3. If number 2 failed, quote me or send a PM.

The problem is solvable.

please help me, I've suffered chronic sinusitis for 3 years, no antibiotics is working.