Have you had a look around the head of the penis? Is there any redness in the area? If so, it could well be Balanitis, which is a little bit of swelling around the area. It can cause itching, soreness, pain when urinating, an unpleasant odour, tightness. I just recently got diagnosed with it following a clear unltrasound and unsuccessful courses of antibiotics for a urine infection and prostatitis.
It can be caused by a fungal infection, in which case your doctor should be able to give you a cream for it. Just worth a thought :)