I got stabbed in the leg, upper thigh area, with a pencil 2 weeks ago. There was a huge bruise around that area. Now the bruise is almost gone, but I have had pain in the same leg from my knee to my hip. The pain is not where I got stabbed though. The pain is like a sharp stabbing feeling, that comes and goes all day. Could this pain be connected to the pencil stabbing? Should I go see a doctor?

Did the pencil break the skin? Any splinters? (The lead is graphite which is inert, so that's not a concern in itself.) Redness where it went in, if it did? Infection can get in. Where exactly on your thigh? Inner, outer, middle, how close to the top?

Yes pain can be referred from another area. But if no skin was broken, I would wait another few days to see what happens. You could have hurt a muscle or nerve in a way unrelated to the stabbing but at the same time, from quick movement of your leg in an awkward motion.

It was the inner thigh, close to the back of the leg on the bottom part of the thigh. It didn't break the skin but it does have a little dot where the pencil hit the bruise around it.Now te bruise is fading, and there is no redness

Did a person stab you, or did you sit on the pencil? Was there any wrestling, did you get up suddenly with one leg bent a funny way? I think you have an unrelated muscle/nerve pain that will resolve with time, warm baths, massage, and tylenol or ibuprofin.

Could it be the cause ? Yes, even the blow or force causing nerve damage. Without an exam in person, no one can do anything but guess.
When this happened did you have a medical professional look at it.

The knee is abused day in and day out just normally. There is fluid there that can leak out and make bones and cartilage etc really rasp against each other. It can be temporary or permanent. Unless you landed hard on it or really twisted it, I would guess temporary pain. Feel all around your knee. Listen to it.
(I had a creaky knee for years after a fall, and had little pockets of fluid under the skin on top that came and went, that were very painful if bumped the slightest bit.)