Will fluid in my ear be an issue when flying?

In about 5 weeks I need to hop on a plane (about a 31 hr flight with 2 layovers) but just today I got a build up of fluid in my ear. This has happened before and cleared up in a few weeks, but if it doesn't, will I be in trouble when the air pressure changes on my flight? If so, what can I do/ will ear plugs help?