Ledge on crown shaved down, but still bothering me. What else can be done?

If you now need a root canal, then you would most likely need the crown to be redone anyway, especially if there is very little tooth structure left.  Suggest your dentist remove (or drill off) the crown, put on a temporary crown, have the root canal done, and then redo the crown.  If, after removing the crown the dentist (or root canal specialist, endodontist) feels the tooth is too small and has a poor prognosis, then you might consider having the tooth removed and either replacing it with an implant or fixed 3-unit porcelain bridge.

If you need to now have root canal treatment on the tooth in question, it would make sense to just redo the crown after the treatment. The lab can create a better margin on the tongue side the second time around.