It seems to me that you might have a condition known as balanitis. This is a term used when there is some swelling, burning and small sores on the skin behind the head of the penis (foreskin). Tight clothing or poor hygiene can lead to this. Try washing gently with warm water and mild soap. Avoid wearing tight clothes and keep the area dry. If it does not improve then see a urologist who will probably prescribe medicine for it.