I also meant to say to try taking a warm (not hot) bath when you begin cramping. Then try to lay down afterward if you can. If this stops the cramps, then it's not labor. Also, Tylenol is safe to take throughout pregnancy.
Cramping is normal during most stages of pregnancy but especially the closer you get to the "big day." Is your stomach getting hard when you are having these cramps? If so and the cramps are increasing in intensity and frequency, def worth a call to your doc. You are getting closer every day, so I'd def pay close attention. Good luck!!! You are almost there!!!
p.s. I have also been having TONS of lower back pain for the past few weeks. it is very low, almost across my tailbone. Random belly pains on & off. The baby has been pretty active.