C.D.
This happened to me on both births. Hate to say it, but although it is "normal" (whatever that is), it could also lead to your having back labor. I had that with both. I'm not really sure what exactly causes back labor, just that not everyone has to deal w/it. Both of my kids were up against my tailbone, too, although yours isn't even near old enough to be in position yet.
Just be prepared that if you do have it, you won't be able to have "natural" birth without a lot of pain if back labor is an issue. I tried to wait as long as I could for the epidural w/my second, not knowing that's what I was having, even though I had it with the first.
As far as the pain now, yes, Tylenol. Swimming is EXCELLENT for helping with this pain, along with stretching, especially the ones sitting on the floor, legs apart, stretching down the middle and each side. Plus, the cat stretch. The cat stretch will not only feel good on all of your back, but also move the baby away from your tailbone. Pelvic tilts are also great, and try do do your kegels - so important. It may be a little painful on your round ligaments to do kegels lying down, so put a rubber ball between your knees. You can also use the Thermal wraps and hot water bottle, plus a bit of ice/cold.
A chiro (one familiar with pregnancy issues-your Dr. may know one) and pregnancy massage (again, make sure that they know a lot about pregnancy massages, as there are certain triggerpoints that can help, harm and even start labor, and they need to be aware of them) can help a lot, too. However, one of my masseuses had great firm hands, but then massaged my tummy. Not good for me. Hurt and made me nauseous.
Good luck to you. I had to use pillows to sit on for quite a while, too.