I have a raised area on the knee cap. it is in the shape of an upside down 7. it is tender and i just had a baby a week ago so is it blood clot?

Varicose vein: Sounds like you might have a small varicose vein on your knee. It really just means that a blood vessel in your leg is swollen. I would expect that one to be kind if squiggly in shape, alrhough roughly like an upside down 7, as you describe. Swollen veins in that location are not usually due to a blood clot.

Thrombophlebitis: It sounds as if this may be a thrombophlebitis which is not at all uncommon during pregnancy and after delivery. See your doctor for confirmation but even though this is a clot, it is not dangerous since this is not the type that will break loose and travel to the lungs. Treatment is basically an anti-inflammatory such as ibuprofen, support stockings, and warm compresses until the clot dissolves.