Left Sided Head Ache, Previous Head Injury, Area Soft, Feel A Dent. Suggestion?

Question: A few years ago, I hit the left side of my head onto a metal pipe real hard. I felt myself spinning. But I managed to stabilize myself and went ahead to school for exams. But my head was really painful. I started getting headaches but I don't have any bumps on the site where it was hit. No nausea, nothing - but headaches for about a year.

Now i have this left sided headache. And when a more painful headache occur, I felt that my world started to move and it will last for about 10-20seconds. Other instances I felt my headache got worse when I moved my head. It felt like the sensation after having your head knocked. When I applied pressure to this part of my head (which I had knocked it previously), it relieves the pain for a while and the site where I had knocked my head was quite "soft" and I can feel a dent on it (which I am not sure if it is related anyway).

I hope you can help. I understand that a visit to a doctor is neccessary for further evaluation, but what I would like to know is the likelihood of the headache in relation to the knock on my head.