I'm sorry to hear about the discomfort you're experiencing. A painless bump on the penis that later becomes painful, swollen, and red could indicate an infection or inflammation. Possible causes include:

• Bacterial infection: This can cause redness, swelling, and pain as the infection progresses.
• Inflammatory conditions: Such as balanitis, which is inflammation of the head of the penis.
• Other causes: Less commonly, it could be related to cysts, abscesses, or sexually transmitted infections.

Given these symptoms, it is important to have a thorough examination by a urologist (a specialist in urinary and male reproductive health). They can diagnose the exact cause and recommend appropriate treatment, which may include topical antibiotics or other medications.

In the meantime, avoid irritating the area, keep it clean and dry, and refrain from sexual activity until evaluated.

Please consult a urologist promptly to get a proper diagnosis and treatment plan tailored to your condition. If you experience worsening pain, fever, or spreading redness, seek urgent medical attention.To narrow down potential causes, we will need some more information.I understand you're concerned about the bump, swelling, and redness. To help me understand better, could you please share your age and gender?