1988 Pontiac 6000 brake lights

1988 Pontiac 6000 mileage 235,000. Four days ago, we noticed that there were no brake lights, so we changed the fuse and they came back on. Then, on Saturday, we noticed that they had gone off again. This time, when we tried to replace the fuse, the fuse kept blowing. We would put it in, and then when we pushed on the brake pedal the fuse would blow. We tried 15, 20 and 25 amp fuses and they all blew out. We checked the relay that the hazard lights and the brake lights are on, and the points were burnt. We filed the points down in the hopes that this would work. We tried another fuse and again and when we pushed the brake pedal down the fuse would blow. We have tail lights, and the hazard lights work, so we think that there is a short, but we can't find it. Do you think that's what it is? We really need to have this car fixed because we use it everyday. Could you please tell us why the fuses keep blowing when we push on the brake and maybe where to look for a short if you think there is one? I really hope this makes sense to you.