Why are my radiators cold?

Yesterday one of the radiators in my house was hotter than the others so I bled the colder ones. As I did this water jetted out continuously with no sign of slowing down. Today the radiators are much colder with the exception of the one that was the hottest before the bleeding (also nearest the boiler). The water pressure indicator is always on high despite it been quite the opposite. Yesterday after bleeding the radiators it dropped but today has risen back to high. Does anybody know what could be wrong? Thanks you