Whats the cause of a missed periods by 4 days with negative pregancy test. this is not 2nd time this has happened to me in 4 months?

Period delay: After 35, the ovary needs more stimulation to ovulate. If ovulation then occurs, the period will begin in about 14 days (if not pregnant, of course). A delay in ovulation is therefore going to delay the onset of your period. This kind of effect can be avoided by using oral bcp's, (if there are no contraindications) also reducing PMS and the effects of estrogen withdrawal.