ssi standard requires the student to dive to at least 15 feet for 15 minutes for each dive. that is the "minimium" standard.
but even if you were planning on only diving to 10 or 15 feet for the rest of your diving career you would still need to be able to demonstrate to your instructor that you can safely equalize your ears.
you should be starting to equalize as soon as your head hits the water. some start before they even start to descend. then you need to keep equalizing as you continue to descend. try swallowing, stretching out your neck, yawning, pinch your nose while swallowing, and pinching your nose while gently trying to blow out your nose.
make sure your sinuses are clear before attempting any in water scuba activities. if your doctor clears you to do so, you might try a good decongestant.
bottom line is that you need to be able to equalize in order to get certified. period.
i agree with someone above who recommended seeing an ent that is experienced with scuba related issues. not all doctors are created equal.