okay i am a healthy 24 yr old who has been on birth control for the past 5 years. I just finished a pack 2 weeks ago, got my period, and was fine. When i started the new pack a few days later i noticed some spotting and then it went away. now in the second week i m having sort of like a light period but it goes away within a day and comes back in the morning. i have been having lower back pain, nauseous, light headed, and very tired. Is there a possibility that i can be pregnant or what could it be?