Quick question, can a cleric change his domains? The domain I want to switch to is within my deity's domain list, so I don't need to switch faith.
There is an optional rule called retraining from Ultimate Combat supplement. Keep in mind that this is from supplement and this rule is optional even if your DM actually applies that book, so consult your DM before using this solution.
Many choices you make about your class features can be retrained. It takes 5 days to retrain one class feature. Training requires spending time with a character of your class whose class level is at least 1 higher than yours and who has the class feature you want. For example, if you are a 5th-level illusionist wizard and want to become a necromancer, you must train with a necromancer of at least 6th level.
Cleric: Retrain one domain; the new domain must be one granted by your deity. Doing so replaces your list of domain spells and your domain granted powers. If you are a neutral cleric of a neutral deity, you can instead retrain whether you channel positive or negative energy, which also changes whether you spontaneously cast cure spells or inflict spells.
(Excerpt from Retraining in Pathfinder SRD. Emphasis mine.)
So, if retraining rule is allowed, you can change your Cleric domain by retraining. To do so, you need a cleric who has the domain you desire and has more levels in Cleric than yourself. It is unclear whether the trainer must have the same faith as yourself, but I assume it is the case.
I wasn't able to find anywhere else where you can change your domain. So, I think retraining is your only call.