For about two weeks I have mild pain in my lower back and I can feel my kidneys quite easy, what could it be?

Some thoughts. Pain in the lower back is most often from muscles. Kidney stones that are being passed usually cause very severe flank pain, but very rarely on both sides at once. Kidney infections can cause flank pain, but usually not mild and fever and vomiting are often associated. See your primary care provider to sort this out.
Poss infection. Back pain may or may not mean kidney infection. If fever or UTI symptoms ( burning or smelly urination) then it is likely a kidney infection ( pyelonephritis ). Wonder if you actually are feeling the kidneys. Usually they are felt unless are enlarge like having obstruction or bunch of cysts. Also, muscle changes could feel like that. You need a doctor to examine you and may order an ultrasound/ua.