Hi, I Am 38 Weeks Pregnant And I Fell Earlier

hi, I am 38 weeks pregnant and I fell earlier today taking my dog outside. I landed on my knees and elbows and mowed my lawn yesterday. I'm having lower back pain that is probably a 5 or 6 on a scale from 1 to 10. I'm wondering if this could be the start of labor, normal pains associated with pregnancy/mowing my lawn or if I need to worry about something being wrong.