What Causes Scalp And Ear Area Pain With Increase During Stress?

I have always a feel of swelling pain on my left part of my head scalp. always having a mild pain on that area up to left ear. The severity increases with stress or tension. The problem persists for about 8 years .I believe that due to this my concentration and thinking ability became poor which reflected in my studies and hence in my life. I am 28 now. Please tell me approximately what could be the reason.