Should I Be Concerned?

This morning I woke up with bad back pains that kept me up most of the night. Then when I went into the bathroom to do my normal routine of getting ready in the morning I noticed that my baby bump was low than normal. Could this be him dropping? I went to take the mail to the mail box and started having some light menstrual cramping. I'm 35+4 weeks pregnant. Could I be going into labor? Have other moms felt the same at this point in their pregnancy? I would love to know since I am a first time mom and don't know what to expect.