As some have alluded to above these are different drugs delivering different reliefs. Also agree that it is dangerous to offer or accept advise in such a location as this . Please do re-consult your doc and provide him/her with your concerns and experience of both drugs.
Co-Codimal is a pain killer
Diclofenec is an anti inflammatory.
Hope you get back on an even keel soon.
Very sensible post, though I would say that if you are in intense pain as described, co-codamol is a bit of a non-event.