Options for a tumor-like growth for senior cat

My 18-year-old tabby developed a swollen nipple maybe in the first quarter of last year. In June I took her to the vet, and at this time the nipple was roughly a bit less than a 1/4 inch wide and roughly 1/4 long. It was pink, not dark. The vet put her on antioiotics for a week, and when that didn't clear it, he concluded it was a mammary tumor and said Topaz needed surgery. Given her age and heart murmur, there's a risk she would die from the surgery/anesthesia. I took her to another vet, who said it didn't look like a classic case of a mammary tumor. We did x-rays which were clear as well as a blood test and urinanalysis. Everything was basically normal except for a couple of small below-average numbers that the doctor wasn't concerned about. The second doctor didn't recommend anything other than surgery as well. I went back to the first vet and we checked out her heart. The technician concluded the murmur was minor and overall her heart is ok.

I've been keeping my eye on it for the last several months. Just this week I found that she appeared to have bitten her nipple, maybe because it's uncomfortable and she tried chew it off. There was a shiny dark pink patch on the nipple and the area around it is more swollen. Tonight I looked at it again, and the dark pink area appears to be crusting over like it's trying to heal. But the swollen area might be a bit darker under the skin. 

I don't know what to do. These two doctors want to do surgery. Are there any other options? Should I convince one of them to prescribe antibiotics to prevent infection of what she just did to herself? I should also say that all this time her appetite, energy and spirits have been normal.

Thank you

Also, as a tangent, she has a large piece of tartar at the base of a tooth. Since a teeth cleaning also requires anesthesia, I've been afraid to have to removed. I had a vet once who manually popped off a piece of tartar during a routine exam. Is it a good idea to try to do this myself? My boyfriend is good at holding her down, but I'm not a vet... Are there options for her given my fear of putting her under?