What Causes Redness, Itching And Burning On Penis?

Hi, I have been experiencing redness, itchiness and a burning sensation on my penis. Been like this for about 6 weeks now. I saw GP and said it was thrush. He prescribed a capsule called flurolexin I think which I was to take 1 only a week apart. I took the second 1 today but there has been no change. What do I do know?