Somethings wrong with my puppies paw? what do i do???

My puppy is a jack russel terrier/pug [[Jug]] about 10 months old (?) and he isnt walking on his right paw. he likes to fallow cars around, and my mom babysits, so she thinks it may have been hit this morning. there is no blood, he just holds it up as he walks and you can tell hes trying not to step on it. i dont wanna have him in pain but eventually he will have to go outside to go to the bathroom. my mom works a second job and has my cousin babysit two days a week and she just left. im only 13 so i cant drive, but my cousin is 18 but cant drive.does anyone have any idea what might be wrong with my puppy and what should i do?