1995 Oldsmobile 88 radiator problem

Good afternoon I was wondering, last month I took my car to a shop because it was over heating and the machanic told me that I needed my radiator flushed so that's what he did. It was running fine and it still is but it wouldn't blow out any heat so I put some antifreeze in it yesterday morning, well the heat started blowing just perfect but when I went to drive my car I noticed that the antifreeze was leaking out and it wasn't just small leaks it was a small size puddle so I moved the car and to see if it still was leaking and I get up this morning and it was. Can you please tell me what's wrong and how I should fix it or what needs to be fixed. And is this a problem that needs to be fixed right away or can it just wait for awhile.