What Causes Chronic Allergies Causing Nasal Congestion Despite Taking Benadryl?

I use to take Ornade capsules for allergies with cold symptoms. I've been off of them for many years. I'm living in Fort Worth, Tx and have had to live on Benadryl the whole 11 years.. When the allergies are high count, my tonsils get tender and I get very sick with a extreme runny nose and lots of clear drainage. I get so weak from it that it takes around two weeks to get over it and regain strength. Years ago if I was without ornade I'd get very sick. Nothing seemed to stop it. I could take 2 ornades and with in 20 minutes it was all gone as if it never happened.. I asked a doctor about a few years ago and he said take Benadryl, that Ornade had been know to cause seizures and he didn't prescribe it anymore. First, is this true, and second is it still on the market