My Guinea Pig Does The Same Thing. Don't Worry. Try Reckognizing How They Act Before The Go To The "Bathroom" . They Don't Like To Poop On You, Trust Me I've Read Up A Lot On That. My Friend Has Had A Guinea Pig For Four Years And Now That She's Had It So Long It Doesn't Poop On Her At All, And When It Needs To She Knows How It Acts, And Will Put It In It's Cage. Try Giving It Lots Of Love And Treats [Mostly Bell Peppers, Handfed] And It Will Start To Know You And Love You Back. Good Luck Dude!