How to know if there's current leakage or battery is dying?

[zirconxi_imp]

Hi all, I had a 9 months old AGM battery installed in my CB that is getting low to crank if I left the bike for 3 or more days. Had taken it out to shop for charging and shop had tested it and says everything is fine. But after I install the battery and left the bike for 3 more days, its getting low to start again. I had taken out the battery and charge it before, and left it after charged for a week before I install back, it crank ok, but after 2 more days it can't crank anymore. So how do I know if the bike is leaking current somewhere (my main suspect) or my battery is dying and can't hold current once I use it?
Do our CB use lots of current when the key is off??
Can I test if there's any leakage just by using multimeter? In normal circumstances I would just buy a new battery, but I am afraid the bike might have other problem other than battery....