9 month old being aggressive

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Hi everyone, I’m just hoping to get some advice with my pup, I’ll try and detail as much as I can -

we’ve had Reuben since he was 8 weeks old, he is now nearly 10 months old

he is well trained, house trained etc

however in the last couple of weeks he appears to be getting a lot of fear aggression. The first instance, we went to a dog friendly hotel for a night for my birthday and Reuben didn’t like the idea of being in the room and hearing people in the corridoor, he started barking (big black eyes, puffy tail) and I (probably stupidly) went over to calm him down and he bit my arm (drew blood and bruised) i stopped moving so he would let go, went into the bathroom and then we went to dinner, we ignored him before leaving him alone and when we returned he was very happy to see us. 

The second time, myself and my partner were on a walk, my partner was up ahead and Reuben was pulling loads trying to get to him whilst I was trying to get his attention on me, asked him to stop and sit, he wouldn’t so I stepped infront of him and he bit my leg and arm again (drew blood, bruised) I wailed, shouted No and walked on ignoring him.

the third time, I was sat in the kitchen between Reuben and the front door and was setting up a nice treat puzzle game when he VERY suddenly barked, big black eyes, puffy tail and went for my arm again! 

I just got him off and then sat there crying - he laid down a few feet away from me with his back turned - I ignored him for the rest of the evening. 

 

A bit of back story, he has recently started barking at the front door (even in the middle of his food) we ignore his and he stops quickly and usually comes running up to us (as if afraid)

We own our own dog friendly cafe and Reuben comes to work with us everyday, nothing in his routine has changed recently - however I am wondering, as he is a puppy and we’re training him inside he is leashed to his bed, he gets a 15 min walk in the morning and evening and between 1-3 hour walk in the day with dog walkers, but perhaps he feels trapped in the cafe? 

He is such a loving dog, enjoys cuddles, merting new people and loves everyone he meets.

he is extremely submissive, when he meets a dog he will crawl on the floor to greet and then roll on his back, he also does this when customers go to greet him in his bed.

 

please if anyone has advice? I am planning to take him to see a behaviourist but wanted to see if I can do anything in the mean time? I don’t ‘punish’ him as such after the attack, apart from ignoring, as honestly i’m afraid if i do, he’ll attack me more.

he has only bitten me but has gone for my partner once to which he got a smack and dragged off

 

thank you if anyone can help, feeling extremely desperate, scared and alone with this!