Turns more red some times for unknown reason and doesnt itch

Red patches on my arm in three spots.

Its been a few weeks now and it wont go away im starting to get concerned everything i look up seems like it may be skin cancer.

very difficult to give an opinion without a picture. Are they raised/bumpy? Sounds like  angiomas which are quite benign ,but to get a proper diagnosis do see your doctor

If they are itchy,spreading in size or number,weeping, bleeding,crusty then it is imperative you see a doctor

Please dont worry even if your doctor suspects a skin cancer. Many of them can be easiy removed