What is the fifth moon-like object I saw around jupiter through my telescope?
A seventh magnitude star.  See this link:

http://www.cloudynights.com/topic/533968-jovian-events-414-1516/

Further info: the star in question was probably HIP 54057 (also known as SAO 118636 or HD 95848.) On April 12th it was occulted by Jupiter (that is, Jupiter passed in front of it) for about three hours. So the star would have been in the area of Jupiter for a few days.