Keep hearing bashing sound in right ear.

Keep hearing this bashing (blub blub sound) like a pulse but it doesn't correlate with the pulse. It occurs at random but always at night. It doesn't have a fixed frequency.. goes away for a few seconds/minutes then comes back. Has occurred twice in the last month. Morning when I wake up it's not there. Always in one ear. About 2 years ago, I have had a brain mri because I was feeling light headed (this was due to iron deficiency) and everything came back normal. Since then I have been fine but have always had low iron. I also have GERD and mainly heartburn at times. But this ear symptom is a new one that started this last month. Is there anything serious? Do I need to get checked? Why does this occur? I also use apple ear phones every night to listen to music while sleeping.