What Causes Pain In Leg While Walking?

I am diabetic and was recenlty hospitalized for Diabetic Ketoacidosis and UTI. I am 30 years old and am 96 Kgs, I am 6 Ft tall. I take my meds recently. Around 6 days back i got a sudden pain on my left leg which made is very painful to walk. I went for Physiotherapy. The pain is there only when I walk, not while sitting or lying down. Can you suggest what it is?? Should i see an Ortho???