I have a small hard lump in a vein on the inside of my arm by my elbow. it radiates pain and stings when i touch or squeeze it. what is it?

Thrombosed vein: It could be a thrombosed or clotted vein. These are common. It will probably go away. If it really bugs you, it can be excised.

Phlebitis likely: Phlebitis is simply an inflamed vein. It could also be thrombophlebitis with is an inflamed vein with a clot in it. Both respond to compression, ice, heat, rest, elevation, and anti-inflammatory medicine. The concern is that there is no clot extension into a deeper vein. See a doctor who can check your veins with ultrasound and make sure you don't have a deep vein clot.