I went on a strenuous mountain bike ride Saturday. I had a few minor falls but nothing major. I greatly exerted myself. When I woke up Sunday, I had a lump under my armpit. It is very sore. I am assuming a may have bruised my lymph node/s. Would that cause swelling and pain?
Hello, Looking at your details it does not look to be a bruised lymph node. It may be an enlarged lymph node due to presence of infection or wound in its Chat Doctor.  You may have an anti-inflammatory analgesic preparation like Advil and check for any infection or wound on affected side. In routine practice, I used to combine anti-inflammatory agent with an antibiotic (Broad spectrum). Hope I have answered your question. Let me know if I can assist you further.