I always get sick right before my period. for example the last 2 cycles i had sinus infection and bronchitis. what can i do to improve my immunity?

Many things: Right before your period is a vulnerable time for your immune system. Some options are to use continuous birth control pills so you don't have the slump in hormones, or you could go on a low glycemic diet, take probiotics, or get a check up with your pcp.

Immunity: Good suggestions by Dr. Metzger. Drink at least 8 - 8 oz glasses of water /day. Try for 8 hrs of sleep/night. Aim for 5 servings of vegetables & 4 of fruit per day. Use whole grains. Avoid or reduce sodas, alcohol & junk carbohydrates. Consider quality probiotics. Maintain healthy weight. Exercise regularly. Manage stress. Don’t smoke. Wash hands often. Stay positive.