I actually just had a bought of this myself. Based on what you've said, my guess is your daughter probably has the same problem...a large amount of ear wax has lodged itself over the ear canal and is causing a build up of pressure. She won't be able to pop her ears without getting that wax cleared up. There's a couple of things you can try. First, you could try one of those over the counter ear wax removal kits. But that didn't help with me. I actually had to make a solution of equal parts rubbing alchohol, hydrogen peroxide and water which I then used to flush out my ears by filling a bulb syringe with the mixture and squirting it (gently) into my ears. It took several tries but pretty soon, the solution broke up the wax and cleared up the pressure problem! Here's a little "how to"...http://www.ehow.com/how_###-###-####_flush-out-ear-wax.html
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I'm a 33 graphic designer, married for over 13 years with four children (2, 4, 6 and 8 yrs). I recently developed an interactive website geared to teaching time concepts to early learners as well as offering tips and tricks for parents and teachers. Check it out at www.mytimecalendars.com. I am also the principal designer of PoleStar Graphics offering graphic design solutions at www.polestargraphics.com.