My bite is not high after two adjustments but my tooth is very sensitive to touch/bite! To Crown or not to Crown?

I had a hole in my old amalgam fillings, so my dentist removed those and filled my tooth with composite. Before the filling I had no pain whatsoever. Now, my tooth is painful when I bite. I have had it adjusted twice and it doesn't feel high at all. It is also painful when I very softly touch certain parts of it with the tip of my finger nail. My dentist thinks that it might be a cracked tooth (no evidence in the X-ray) and suggests a crown.