Should you have sensitvity/tenderness/pain when eating crackers, nuts, textured food 1 month after root canal?

A month ago I had a root canal that took 2 visits.  Afterwards there was typical soreness for a few days.  Up until now it has been fine, recent development is when i eat something crutchy, or with texture, and I bite down on the food it hurts, but not all of the time?? It feels like the pain/tenderness is on the surface of the crown, it does not feel like it is deep in the tooth.  There was a small amount of blood on my floss one time. I do have sensitive teeth and sinus problems with some congestion and a sinus headache but that is subsiding. I plan on contacting the dentist but should I have cause for alarm??  

[Jerome Tsang, DDS]

Is it an upper tooth?  If it is and you're having an active sinus infection, its possible it can be from the sinus and not from the tooth itself.  Timing would most likely give you a good idea if that's the case.  If the sinus and toothache started around the same time, it may be more likely due to the sinus.  Did the crown hurt initially when placed?