joints pain demotivate to exercise

Both my knees are painful and my elbow starting to hurt too. I feel like every exercise is hard to do. My friend suggest that I try swimming but my elbow hurt so much when I try to swim. I had stop exercising for 2 days to rest my joint hoping the pain will go away soon. today I try to do some low impact exercise but I am sweating heavily after 15 minutes because I can feel my knee begin to hurt. anyone have the same problem? can give some exercise advice?