After taking the my second pfizer covid vaccine i have pain/tenderness in my left armpit and the side of my neck. read that it could be lymph nodes, but they dont feel swollen, just a bit of pain if pressed. started the next day after vaccination?

Normal immunity: Lymph Nodes are localized glands which grow large temporarily to accommodate more infection fighting cells and filter out debris and broken cells from the lymph due to an infection. This is a normal process and can indicate that the immune system is fighting off an infection or recruiting cells to recognize and build an immune response to a vaccine. The swelling lasts 1-3 weeks then recedes.

Expected reaction: Your local response to the site of injection is not uncommon for vaccines and is neither localized damage, nor a cause for concern. Not likely swelling of lymph nodes per se early on, and highly unlikely to represent infection. Might last 2-3 days, and fade.

COVID 19 vaccine: After vaccine, tender or enlarged lymph nodes is due to body developing an immune response. Nodes usually return to normal size w/i a couple of weeks - up to 2 months. If nodes have not decreased in size by 2 months, get eval. REF: https://www.wkyc.com/article/news/health/coronavirus/coronavirus-vaccine-swollen-lymph-nodes-university-hospitals/95-ff7d0123-4246-452e-88ba-02daec9bd15c