How to get rid of ear congestion?

I had what seemed to be the stomach flu almost a week ago and a few days after that I still had headaches off and on and my left ear just seemed to pop. It didn’t really ever seem to unpop, I can’t notice it all the time but it starts to hurt when I blow my nose, and it’s like I can hear it being clogged and not able to pop. I also have seasonal allergies right now. Is there anyway to get this to stop? ?