Is Lower Back Pain The Indication Of Pregnancy?

hello dr i got married 2 years back and i still trying for baby in this month 1 fel like some changes in myself like lose my weight ,i was 62kg now i m 58kg and my period date was last month is 6may2011 and its cycle of 28days tell me dr is lower back pain in this week is symptom that i conceived and what type of care i do in the last week before periods that i concieved baby