I get something similar. Doesnt happen to often, but will happen after a stresfull day. Can happen in either ear. Its not a ringing, but more like I can feel the heartbeat in my ear/fluid is moving around. Best way I can describe it. Doesnt last long either, and only happens if Im moving around. Actually happened this morning. Weird, dont know what causes it. Its not painful, just annoying and lets me know im about to get a severe "pressure in my head" kind of headache.