What Causes Blood Blister Under The Nail To Spread?

I hit my finger, just below the nail and the first joint last Sunday. It s been throbbing/tingling with pain since. A blood blister formed under the nail and continues to grow. I went to Urgent care on Monday, took X-rays and nothing is broken. The dr didn t drilling/cut a hole in nail because she believed the injury was lower on the finger and not under the nail. She thought drilling the hole wouldnt relieve pressure and wouldn t really help the situation much. At that time, the blood under the nail was only about 1/4 - 1/3 way up the nail bed. Today, it s all the way up the nail and has spread a little beyond the nail (still under the skin) on the one side. You can still see it bumped up under the nail, where it got hit. Should I be going back to a dr or is this normal to keep spreading? How long does it take before blood under the nail should stops spreading? I have been taking Advil for the pain and icing my finger several times a day. No fever.