I went to the hospital two years ago for back pain, an enlarged spleen ,hyperthyroidism and enlarged lymph nodes were discovered, was treated for hyperthyroidism an the cause for enlarged spleen and lymph nodes was never investigated. I have a hard lump that has been growing since in the last two years behind the knee and is painless however I only discovered it got bigger yesterday when I went to sleep on my left side of the body and had a horrendous pain in my thigh muscle and over the last two years I have had a feeling like I am dragging a heavy steel ball in that leg. should I be concerned? I am 36, non smoker , height 154 cm, weight 62 Kg.