What Could Red, Small, Painful Eruptions Below The Knee Mean?

Dear Sir, my wife aged 25, is suffering from small red painful eruptions(lesions) below the knee till the toe area. These were first observed on feb 2010 and on consulting an orthopaedic, she was administered the following medicines:1) Tab Defza 2) Tab Zocef 3)Tab Sompraz. On taking these medicines the eruptions , swelling & pain got temporarily cured but again the same recurred in the month of september 2010 & again on December 2010. The problems still persists(& the eruptions are increasing) & due the irritation & painful swelling she is having difficulty in movement. The areas become stiff while she is seated & experiences difficulty while getting up & walking. Can I get an idea of what may be the cause of it & what is it? She is currently having normal diet & we dont suspect allergy to any food.