The inside of my molar is subtly painful and itchy. Does this mean the nerve is dying?

The inside of my molar is subtly painful and itchy; does this mean the nerve is dying? 2026.07.13 22:52:01 +I have a molar that was filled with a gold inlay on August 19th of last year at 5 PM. For some time now, the inside has been itchy and throbbing subtly whenever I eat sweet foods, and the symptoms have worsened as I continued to eat sweets. Now, even when I eat hot food, it suddenly throbs, hurts subtly, and itches a little. (This symptom was on the evening of July 15th.) What is more serious is that even when I am not doing anything, there is a symptom where it throbs subtly and itches for about 5 seconds. I tend to skip brushing my teeth often; could this be secondary decay or irreversible pulpitis? I would like your opinion on whether I need root canal treatment. (I couldn't take a picture because it was difficult; please understand.) Since yesterday, I have had a tingling pain in my molar, and it is the same today, for about 5 seconds. It is not excruciating, but it hurts subtly. Why are symptoms like this appearing? Most recently, cold water touched my molar, and it was sensitive for 5 seconds, so I was surprised. A symptom that developed recently is a tingling sensation in my molar for 5 seconds. It isn't excruciating pain, but it is a subtle, stinging ache. I thought it would get better if I just left it alone, so I did, but it seems to be getting worse. Could this be a secondary cavity? It gets worse when I eat sweets. The tingling sensation in my molar for 5 seconds isn't excruciating, but it is a subtle, stinging pain that gets worse when I eat sweets.

I felt a subtle tingling sensation for 5 seconds. It wasn't painful, though.

This is a symptom I didn't have before, but it appeared again today.

The dentist told me back when I had the cavity removed that it was deeper than expected, and he even mentioned the possibility of a root canal.
Also, recently my molar has been throbbing a bit and I have a slight headache. What could be causing this? As for the last additional symptom, I chewed some sour jelly with my right first molar, and it really stung, which surprised me a little.