My allergies cause me to not be able to equalize pressure in ears?

I have never really had problems going to the bottom of the pool when I was a kid but when i hit puberty i started getting allergies and got really congested. So last summer I tried to get SCUBA certified and I couldn't because I had to much pain in my ears and sinuses because I couldn't equalize the pressure change. I have tried decongestants and allergy relief medication but nothing seems to work, maybe it has something to do with puberty and growing and maybe in a few years I will be able to equalize and dive but if u have had the same or similar experience please help me out and give me your thoughts on whats happening because I have a lot riding on me being able to dive. My sister had a similar experience she had bad allergies when she was my age(15-16) but as she grew up (17-18+) the allergy symptoms died down. any help will be much appreciated If you had something similar happen to you please help. Thank you for your time.