I can speak from experience when it comes to flying with blocked ears. Build up of fluid in the inner ear occurs due to an inflammation where the eustachian tube meets the back of the throats. (BTW It is likely that if you have suffered from nothing but a soar throat for a couple of days, that if you go flying, you will end up with a blocked ear during the descent. This can be very painful.) It means that the only exit for fluid or air is blocked.
So you cannot go flying in ANYTHING!! If you do, you risk rupturing your eardrum and possibly also doing damage to the internal mechanism of your ears. (ie you will sustain some degree of hearing loss).
The only way to get away with is to fly in a pressurised aircraft which maintains cabin pressure at sea level. Airliners fly with a cabin altitude of 6000-8000 feet! The risk now is that if the aircraft suddenly depressurise, you will probably blow the side of your head off. Is it worth the risk? You decide.