Scabies is a mite that can infect the skin and cause a lot of irritation and itching. It is obtained by touching a piece of contaminated clothing other substance. It is quite common, and should always be considered whenever someone develops an area of skin that itches really bad. I will say that the pattern of itching that you have is not typical of scabies. The most common locations for scabies to hang out is the webbed area between the fingers. There may small dark spots where the mites have burrowed into the skin. The knees are not a typical location, but it certainly can happen. Plus, little red bumps sound more like a type of dermatitis rather than scabies.
I suggest that you schedule an appointment with a dermatologist
. A dermatologist has the expertise to be able to look at the pattern of itching and any other skin findings and determine what you have. If it is scabies, then you can get the prescription for the cream which will kill the mites. If you have something like a dermatitis, then you can get a medicated cream such as a steroid cream to help calm down the itching and get you feeling better. Good luck.