Root canal/ crown pain, ow! Could my dentist have messed up?

It is normal for teeth to experience pain sometimes after a root canal.  There are several things that could be contributing to the discomfort that you are having.  1. Normal postoperative pain.2. Tooth is touching whe you bite causing bruising.3. There is a crack in the tooth.Schedule an appointment with your dentist right away to have it evaluated.  It is unlikely that your dentist is the cause for your pain.  Good luck. 

If I understand your question correctly, you are having pain in the tooth NEXT to the root canal tooth after it was prepared for a crown.  The tooth that is having pain may need a root canal as well.  Depending on the condition of the tooth prior to the crown (ie decay, old fillings, trauma)  the root canal may have been needed and not because the "dentist messed up".   It is not uncommon for a tooth to require a root canal after it is prepared for a crown.

It is not uncommon for a tooth without a root canal to have sensitivity and aches due to the preparation of the tooth and the resultant exposure of the sensitive area of the tooth (the dentin).  Keep in mind you had surgery on this tooth, any other part of your body you would expect to have some recovery period, your teeth are sometimes no different.  The temporary crown and temp cement do not seal and bond to the tooth and can allow cold, hot and even pressure to cause discomfort. Obviously without being there when the procedure was done and not having any x-rays it would be impossible to tell you if there are other issues going on.  I would contact your dentist and see if he/she has any concerns other than normal reactions after the procedure.  The real test will be after the permanent crown is cemented; it should have less or no sensitivity and feel much better.  Be patient and try not to look for reasons to distrust your dentist, most of us are good and honest people.