I have a lump about an inch from my knee cap on the inside of my knee that is painful.

Varicose Vein?: Based upon your description, the most likely cause for your symptoms is a varicose vein, which is an enlarged vein that can sometimes become thrombosed (have a blood clot in it) and can become inflamed and rarely infected. I would discuss this with your primary physician for additional recommendations and care, but also to rule out a deep venous thrombosis.

Varies: There are numerous possibilities. It could be an inflamed area near what is known as your tibial tubercle. I would not hesitate to be seen and evaluated for it.