My boy also had this problem when he's small. The doctor wrote as a name and we bought a bottle of oil (like Olive oil) in Watson's, it was used to clean the earhole. The first time was unsuccessful, but when I tried the second time the next day, after I put the ear drops, I let my boy's head holding for quite sometime (he was lying on the bed), the other earhole was the same. After somewhile, I could use the "old" and "traditional" tool (like a small long pin with a round head) to take out his "dirty thing" inside the ear, a very long "tissue, dark brown in colour and have some smell.
I think the oil is OK, but that when applying, it's good to let the oil goes inside the ear hole for quite somewhile to "soften" all the "long dirty thing".
And now, every night, after he washed his head, I use cotton puds to clean his ear hole and periodically use that "long pin with a round head" to take out the small dirty thing inside. So far his ear hole is very clean.