There's a cheap book you can get from www.dogwise.com called "Preventing Dog Aggression" that teaches you how to handle a rambunctious puppy like this.
A 5 month old really is just using it's mouth inappropriately and needs to be taught putting teeth on humans is not acceptable. In my house, this act earns my dogs a "time out." We immediately stop doing what we were doing, I stand up, walk away, do not give them access to my hands, and ignore them for a minute or so (they must settle themselves down). Tugging on my pants or barking for my attention gets them nothing in return. I don't reinforce positively or negatively, they just get neutral from me. Once settled down, we interact again, althoguh typically at a lower level of stimulation than before. I'd also redirect them to something appropriate to chew on at that point. Carrots are a great substitute as well as Kongs stuffed with goodies and bully sticks. Puppies need to chew, but it's not ok to chew on me or people. I too have young kids in the house.
This isn't somethign that will work overnight, but consistent non-reinforcement for an undesired behavior will give them the message over time.
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Chelle and the rest of the crew including, but not limited to Kita and Taiko (the shiba inu wrestle maniacs), Adi (reserved and dignified tabby cat), and all 28 reptiles