I have a 5 yr old male Chihuahua named Pupito, earlier today he was excited by something and his penis came out, it got very swollen and turned a purple-ish color. When he stood up from where he was I noticed that he was also bleeding...not profusely (a few drops), but enough to worry me. I don't know if that's normal when they get excited or if there's a medical problem that causes this. Please help?