Cold Water problem?

Hi, I have just changed all the taps in my bathroom, the basin ones and the two free standing taps on the bath for a mixer style with a shower head.

Before the tap replacement - I turned off the water supply (downstairs stop valve) and the tap down stairs went off, I then went into the loft and turned off three valves (two from the cold water storage tank and 1 feeding another smaller - header ? tank). Both taps downstairs now don't flow, hot in the bathroom doesn't but the cold upstairs took ages to drain the cold water tank - which drained and didn't refill.

After the tap replacement, I turned on all 4 valves. Downstairs hot and cold are running fine. Upstairs hot is running fine, cold at the start was non-existent. I left the cold water storage tank to refill, which it did, now the cold water tap runs quickly for a second, then really slowly until it almost stops. If I turn the cold water tap on, the toilet cistern stops filling, when I turn it off it starts again - very slowly. The bath mixer cold does the same, quick, slow, trickle, stop. How can I fix this and what do you think had happened?

Thank you for all your help.