FORTUNE -- Dear Annie: I've been at my current job for about four years, during which I've survived several rounds of company-wide layoffs, made it through a huge, disruptive merger, and reported to five different bosses. I manage multiple brands for a wide range of products, and my knowledge of our operations and our customers is immense. My responsibilities have increased steadily since I started, and I'm involved in major decisions at both the strategic and tactical levels. In addition, I've built strong relationships with everyone here and I know my boss likes my work. All good, right? But here's the problem. Strangely, I just found out that a colleague of mine, who has the same title and duties I have but who was hired just last year, is making $14,000 a year more than I am.