Colors bleeding in the wash.

First, what causes colors to bleed? I never had a problem with this until recently and I am wondering if it is caused by the new fabric softener/bleach/detergent I am using. I’ve washed all these clothes before without a problem.

Secondly, is there anyway to get the dye out? I had something blue bleed onto a pink shirt so I can’t just bleach the thing like I did with my whites.

Thank you for your time.

Bump – I’m having the same problem, and I don’t know what to do! I’m keeping the shirt (red and white argyle, the red bled onto the white) wet, but is there some sort of solution (I’ve heard vinegar?) I can make to get the dye out of the white part and/or help it not to bleed again?