If we understand your case, your last interval was eighty-five days, your current interval is already past thirty, and you have yet to bleed again. The remaining requirement for this cycle is to observe your interval day on day 85.
Should you become niddah again before day 85, you would observe: the day of month, the new interval, and the thirtieth day (onah beinonit). (Once you have had three intervals in a row that extend past thirty days, you are not required to observe onah beinonit or the day of the month. If that is your situation, you will observe only the interval day.)
If you do not become niddah until after day ninety, please get back to us and indicate your age as well.