What exactly is the chumras or zarua and am I obligated to keep it?
This is a stringency which adds on to the Onas Havest an additional 12 hours. Meaning whenever the onah falls out, the day or night before is also observed as a vest and one would refrain from relations during that time period as well. While this stringency has become very widely accepted in some circles, it is not a halachic obligation. Perhaps you should speak with a Rav who knows you personally to help determine if this chumra is right for you at this time.