What is my knee lump & what self-care can I do?

[vegasfem]

I've been taking long daily walks. 2 weeks ago I started feeling slight knee pain at end of walks and noticed a soft lump on the front of my kneecap. A few days later, the lump turned firm. It does not pain me except towards the end of my walks, but the lump has slowly grown larger and is apple shaped. I'm incarcerated so unlikely to get medical care. What can this be and what should I do on my own? Any information appreciated.