distinct clicking sound in my engine?

Common 'ticking sounds' are usually your lifters not getting oil (you have lifters if it's a ohv setup or push rod, usually in v engines), your valves need to be adjusted (easy to do if you know what your doing and have feeler gauges) or a rod knock. If it only happens after an oil change, I'd say it's lifters but since your car is a dohc, not ohv, it's probably your valves in need of an adjustment. Like I said easy to do yourself or u might wanna get a shop to do it. Just hope it's not a rod knock, otherwise that new engine was a big waste of money.

Call repair ship!