It is some sort of unreliable Yoga which is not endorsed by Vedic astrology. Is it not meaningless that a certain duration of time based on Nakshathra is good, bad or ugly. These are misuses of astrology employed by wayside astrologers. All the planets act in tandem on all the living beings and Nakshathra which is Moon’s position in the zodiac alone will cause good or bad is meaningless.
Read Navagraha Astrology Online to get a scientific explanation of how astrology can be used in our life similar to roadsigns are being used by a motorist.
4g bad means 4 ghati bad, I presume.