What Causes Ear Blockage?

I was working out doing abs when my right ear made this closing sound. I tried to pop it by putting my finger over the whole and pressing slightly then letting go but with no luck at first. I would get it to open up occassionally but for the past 24 hours it continues to close . Sounds are muffled in my right ear and im not sure why. I cleaned my ears like 16hr before this happened and nothing came out as far as ear wax goes so im not sure how or what i did to it. any ideas