Hi Christine,
Colic is a fairly unusual condition of the dog, referring to an over-production of gasses. as dogs are not grass eaters, then we do not get the gas build up seen in horses/cattle,etc. that does not mean dogs dont get colic, but oftne there is a different reason, eg diet/exercise/arthritis/disease. At eight we might start seeing arthritis of the spine, which could lead to bowel stasis (not moving properly), so that after rest the dog may show pain. may be worth a look? I take it the cimetidine is not working.maybe you could try an absorbant, such as charcoal? Presuming all esle works ok, then it may be that an xray of the spine could be worthwhile,