Iron filter problem

I have an Iron filter for my water that I had rebuilt about three months ago. It's been working great up until today. The deal is, I put a new dose of potassium in the potassium tank today because the water was starting to smell again. It had been three months since it last got a new dose. The water had been smelling for about two weeks, so I thought that after I put in the new potassium, I would run a Manuel back wash on the system. I probably shouldn't have messed with it, since I don't know a thing about the it, but I couldn't see what it would hurt. I depressed the red button and turned it counterclockwise to 'start' as the instructions said. It kicked on, so I left it, thinking it would run whatever check it needed to run and then shut itself off. I came back two and a half hours later to find it still running. Clear water was shooting out of the outlet hose. I depressed the red button again and turned it until it shut off. The problem now is, my water pressure is very poor. I have a valve coming out right at the well head and that pressure is fantastic ... just like my inside pressure was until today. But anytime I rout the water thru the filter, it slows way down. If I flush my toilet, it halts to a drizzle. What did I do? I can't imagine how what I did could screw up everything. I see little purple water droplets forming around the filter head. It's always had a hairline leak in there somewhere, so I think the potassium has made it into the unit. The scary thing is, it's REAL purple. I have an iron testing kit and my iron level has dropped from one PPM to almost nothing in the last three hours. But with this kind of pressure, It isn't even practical to use it. Can anyone here shed any light on this problem? And advice would be much appreciated.
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