After drinking between about 3 to 5 alcoholic drinks if i ejaculate my penis has a burning sensation for about 30 minutes. any idea what this might be?

Prostatitis: Alcohol can inflame the prostate gland in men, and a burning sensation on ejaculation is one of its main symptoms. 5 drinks or more on one occasion (for men) is the definition of a binge, and it is not healthy for you in many ways. I would strongly urge moderating your alcohol use. If the symptoms continue, see your primary care provider or a urologist to have your prostate examined.