One thing I can come up with, and there is a thread on this, is a muscle that attaches to the ear drum that clenches in preparation of loud sounds to help protect the ear. Some people have control of this muscle and other have partial control, and the rest don't have any. Do a search on this site for, "I can make thunder in my ear", or something like that... It's a very long thread.
I too had that problem a few yrs ago I went to the doctor and explained it and they flushed my ears it felt weird at first but after it was done I no longer had that problem again