What Could Cause Long-term Tinnitus That Feels Like Irregular Pulsing In Someone With Hearing Loss And A History Of Breast Cancer?

I have had tinitis for years. It as, in the last 2 years felt like what I can only describe as what an ekg chart would FEEL like. a ringing/buzzing combo that swells in an irregular type rhythm. almost like a flat line,- 5-6 pulses and then a flat line again. it is in my head only, seems like it goes left to right. I have not seen or read anything like it. I do not have headaches and there is no pain. For about 6 months I did get the heartbeat sound in one ear if I laid on that side of my head. That is gone. I am 61 and do suffer some hearing loss (untested). I have had breast cancer in 2004