Random ringing in left ear fir past week. It comes and goes for a few seconds?

Tinnitus. The causes of ringing in the ear could be infection, earwax, dental problems, temporomandibular joint disease, severe weight loss, blood vessel disease of the carotid artery, neurological diseases such as multiple sclerosis or tumor, meniere's disease, thyroid disease. There are many potential causes and if it persists you should be examined.