Air Purifiers

I’ve had my ionic breeze for awhile and really liked. It gave off a nice fresh air smell. I stopped using it (kinda forgot about it when I moved) for about a year. I then plugged it back in and ran it continuously for a week or more. Cleaning it when needed. All the sudden it started giving off this bizarre odor. I can’t really describe it except for it almost smells like dirty dish water. I stopped using it for about 8 more months because of this and then started using it in the room with my birds. It gave off the same smell. I cleaned it over and over and no difference. I decided if I ran it continuously maybe the smell would "work its way out". That hasn’t happened. Now after some googling I found out it is potentially unsafe. The stuff I read said it was ozone, but the ozone gave off the fresh smell. So what is giving off this terrible smell? It gives me headaches and now I’m worried for myself and my birds (2 budgies and a cockatiel). In the future should I go with an air filter/hepa filter etc? Thanks for any info about this mystery smell and a good course of action.