Deb,
I had one this summer and I was chewing (carefully) by dinnertime of the day I had it!
Mine was the very last tooth, on top, don't know if that makes any difference.
That was my first root canal, so I don't know a lot to tell you , just that once mine was done, the worst was over.
Was your tooth infected before the root canal? Maybe you need (more) antibiotics.
I think this is worth a call to your dentist or whoever did the root canal.
I hope you start feeling better soon!!