Slight irritation with crown on tooth?

I got a crown on a tooth on my lower left side. It was a tooth on which I got my first cavity (when they used the silver filling). Anyway, I got the crown last August and things for the most part have been fine. However, lately I've been getting some slight discomfort in the area of that tooth. It's not pain, but I notice it from time to time. It's kind of the same feeling I had before with the tooth before the crown. But that discomfort was never that bad that it made me go to the dentist to get it fixed. The dentist recommended the crown on one of my twice-a-year cleanings. I have a cleaning scheduled 2 weeks from today, but it's with a different dentist. There was a financial dispute with the price of the crown at my previous dentist (was quoted a different price and the final bill showed I owed more than $200 than I was originally told). That dentist told me if I didn't get a crown at that time that I would need a root canal. I'm hoping that it hasn't come to that. A crown cost almost $750 with dental insurance and a root canal is even more. Is this discomfort normal from time to time? Or am I on my way to a root canal?
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hard to tell without looking at an X-ray and clinical examination.also can you add more details about the discomfort which you are feeling from time to time? is your crown made of gold or tooth colored material? when do you feel the pain? is it sensitive to temperature? is it hurting when you are eating? when did it started? more detail, better.
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