The doctors aren't "discriminating" against you. The fact is, certain medications are high-risk for most alcoholics to take. I've never in my life had an issue with pain meds--I don't like the way they make me feel (unlike the way I love how alcohol makes me feel--in the short run, anyway). If you don't feel you can communicate well with your doctor, you should find a new one. Lying to the doctor could cause you a lot of problems--alcoholism-related symptoms, for example, could be misinterpreted. If you incurred any liver damage certain meds might be very risky for you to take.
I keep my alcoholism private except on a need-to-know basis. The doc is someone who "needs to know", IMO.