A small part(about 3cm) of the big vein on my left shin is a bit bumped up and sometimes it feels like a worm is crawling that area. what should i do?

Varicose vein: It sounds like varicose veins, There is a possibility it may cause swelling and pain, if so see a vascular surgeon the veins could be treated with laser if it meets the criteria.

Bulging vein: If you are on your feet a lot that vein will be dilated and if you elevate you feet that vein will go down. For more severe cases the vein can be sclerosed with agents.