should I have tooth pulled???? PAIN

Hi, looking for much needed help
Five months ago I had root canal on tooth #3. (since then it has been "redone" at least two more times). Pain/ache has continued in tooth. Got another opinion from an endodontist who looked at x-ray and said things look fine. (he did not re-open tooth to look with microscope as he did not want to traumatize tooth any more)
Ever since I had this root canal the pain continues. Just before dentist started root canal, I also was experiencing a mild ache in my upper teeth (opposite side of root canal) which has now grown to be very painful at times especially when I talk or eat. Before I had the root canal, dentist tried putting crown on tooth (saying he found two cracks in it). Although all the x-rays before the root canal "looked normal" once the dentist openened it for root canal, a large infection was found.
Can one tooth cause trouble with the whole mouth? Is it possible that the infection/root canal disturbed nerves along my upper teeth causing this terrible pain? Please help.  I would have the root canaled tooth pulled immediatley if I knew it would resolve this mess. Has anyone experienced anything like this?
Thank you for your help. Much needed.

[Jerome Tsang, DDS]

I would recommend seeking another endodontist's opinion on the tooth before considering an extraction.  Its possible there's a fracture on the tooth that isn't seen and could be the source of pain.  

Yes, pain can be referred, meaning it feels like its spread out or jumps to certain areas that the nerves travel along.