Back Discomfort

On 6/19 I was playing basketball and I got undercut a little bit.. I fell on my tailbone/back, I then also hit my head on the blacktop surface.  Now, I immediately went to the doctor since I did hit my head and I wanted to be certain that was nothing to be concerned about.  I went to the doctor on 6/21 and he ran a few basic tests on me and said due to my vitals there was nothing to be concerned about.  My head still feels fine so I'm inclined to agree at this point.

Anyway, on to my back.  A couple days after the doctors visit on 6/21 I started having some tightness/discomfort in my lower/mid back.  There is no pain at all, just some discomfort, it's definitely more noticeable when I'm sitting down.  It almost feels like putting a small object back there and leaning back on it.  I feel nothing at all abnormal when I'm working out or walking around.  

I hope I gave everyone enough information and I appreciate any feedback as to what might be going on.

Thank you!