So whenever i sit down for awhile with my knees bent when i have to get up my knees hurt really bad and they feel numb and it's hard to walk. help?

Patellofemoral : Sounds like it may be patellofemoral syndrome. It is usually aggravated by sitting for long periods. It's called a "theatre sign". Numbness is an odd complaint but anything is possible.

Many causes: Many possibilities. Often related to knee instability. Have knee medial-lateral stability checked. Then ? Rheumatologist or orthopedic surgeon.