Throbbing pain on 6 year old crown

Morning All

Wondering if anyone can help me.

About 6 years ago I got root canal and a crown done on a damaged tooth (bottom tooth, just off centre)
Last January it popped out so I went back to the dentist and he told me this was normal. He put it straight back in it's been fine up until now.
3 days ago I awoke to a throbbing pain in this tooth and I haven't been able to shift it! I am no way a dental expert or anything and I cannot understand why it is throbbing like this. There are time's where I find myself in a trance because of the pain get's so bad. Strong painkiller's don't seem to do the trick.
Has anyone else out there experienced such pain on such an old crown?
My girlfriend seems to think that I could have been grinding my teeth during the night, thus pushing the crown further down than what it should be and the metal pin at the end of it could be sitting right on the gum, causing an infection.

Can anyone help?

Thanks
Greg (in pain!)

[sijanise]

Id be at the dds  asap in the morning if i were you..maybe youve developed an abcesses? i mean ive been spending the past 48 hours almost non stop reading on post root canal pain and aparently they can go bad even after years....maybe youve fractured the root, or its just an infection..best bet, have them xray it and tell your dds about it in detail.

I have 3 root canals and had my 4th last tues and im going back in in the morning, w/o an appt and basically demanding to be seen. ive spent the weekend in agony after my newst root canal and ive been having the "throbbing"...i think i have a abcesses post root canal or ive fractured the root somehow, even though the root canal was done through an old crown. I think he may have to retreat it (apparently they can do that...retreat a failed root canal, even uif its been yrs) that or im having root canal SX...starts with an A apecio?? something..they open up them gum below or above the root canaled tooth, nip off the tip, seal it, get out any infection, close it up and its supposed to be good to go.

hopefully yours hasnt gone bad that fast...my previos 3 root canals are anywhere from 10 to 5 yrs old and ive never had a crown come off or any pain at all from them, but if i did expeirence pain like youre describing id make an appt...plus im paranoid of things going wrong when it comes to dental work...

also i clench too, im worried my clinching is hurting the new root canal, im gonna talk to my dds about a night gaurd,,,they say clincing and grinding can be super bad on a root canal cus the tooth is more brittle and the tooth or root can fracture from it...so far i havent had any fractures but i know i clinch like crazy cus i wake up sometimes still clinching super tight.