Where's My Red??!!!

I am distressed, mad, annoyed, slightly baffled and a bit confused. I colored my hair about three weeks ago: Clairol Tone on Tone super red. Loved the color. It was great. My hair looked really good, soft, shiny, and that red -- bright, happy, red all right. Yes, I have to say, too cool. So I have the color, feeling good, go swimming in the motel pool, and it was still red for a day or two but suddenly, the color is gone! Just, gone. My hair isn't some weird greenish-blonde color (thankfully, that happened to me once, it was bizarre) it's just a dull kind of brown, with a bit of red highlights. What happened? Was it the pool? This never happened to me before. Maybe it just faded but if so, it's a major fade.

I don't know if I should just color my hair again; or wait. I hate this boring brown color, I want my red back! I suppose I could go get it professionally done but I really can't afford it.