Is there anything I can take for the pain?

I've been dealing with pain in my back for a little while now. When im at home I use a heating pad or place my self in a position that doesn't hurt so much. I need to know if there is anything I can take that would in no way harm a possible baby. I'm close to the end of my TWW & I've been afraid to take anything for fear of harming the possible fetus that I feel like could truly be there? Anybody have any ideas of how to deal with the lil bit of back pain for when I'm out and about?