OMG!!! Please help

Okay so I'm 34 weeks with my second child. 
I have just had a shower and was washing my self and tmi when I got to my butt I felt somthing that wasn't there yesterday or ever before either. It was like a little bubble of skin or sum thing coming from butt hole!! What could this be?? I'm to scared to even look but it's disgusting!! I know "bubble of skin" is a crap description but can't think of anything else to describe it as 
Please help