What is treatment and causes of blocked boils on thigh and back bump?

Hard to say but sounds like furunculosis - infection of the sweat glands and/or hair follicles in the skin. Often causes boils which are swollen and painful. Warm compresses over the site sometimes helpful. If that is not working, you may need to see a doctor to have them lanced. If feeling ill “all over” ( chills, fever, weakness) see doctor NOW