Jada my friend I am certain you already have one but if not invest in a good prong collar and leash, make a quick correction not yelling just a firm no. Also try tethering him to you for a few days, I know its a pain but it will reestablish dominance and alpha to him. and you know this one is coming if you havent done it recently take him to the vet rule out anything physical and then work on behavioral. by the way Jesse saw your siggy and said your babies are beautiful! she is sending some p[ics of her brindles I can post here! I do hope this helps I had a couple pups over the yrs that exhibited this behaviour and with consistent work and reaffirming who really rules the roost they were fine.