How concerned should you be?

Not very concerned at all.

COVID-19 Vaccine-Related Adenopathies Lingering Longer Than Anticipated https://www.diagnosticimaging.com/view/covid-19-va...

"Based on their analysis, the interpreters determined 29 percent of patients had positive axillary uptake seven-to-10 weeks after their second vaccination dose. Specifically, 42 percent, 31 percent, 25 percent, and 19 percent had these findings at week 7, week 8, week 9, and week 10, respectively, the team said.

And, these lingering findings are also being seen with breast imaging. Stamatia Destounis, M.D., FACR, a radiologist at Elizabeth Wende Breast Care in Rochester, New York, confirmed she is seeing the same findings in screening mammography in her practice.

"Now, it can be several weeks later after both vaccines are completed that we are still seeing quite large lymph nodes," she said. "We're seeing them on both sides, and it can take up to 12 weeks for these lymph nodes to go down in some patients."

The other thing to consider is that with breast cancer, lymph node swelling would be on the side that has cancer, it would not be bilateral. So with bilateral swelling, the cause is more likely to be the vaccine or an infection rather than breast cancer.

As for the complicated cysts, a 6 month follow-up screening is standard for those. I've had that several times and have never had any issues - eventually the cysts shrunk on their own.

Hope that helps.