White Foamy Bubbles From Anus? HELP!?

I have been constipated lately, my butthole has been really tight.. so today i was just trying to make sure everything was okay, I bent over in front of the mirror, and kinda strained alittle, and my butt started making this weird bubbling noise and this white bubbly foam stuff came out, it was a little strecthy like discharge... what does this mean?????????