We have a border terrier puppy, 7 and a half months. He's generally a delight - daft as a brush, a happy soul, very easy going, non-barky and mostly obedient if a bit lairy at times.
Last week we were away in our campervan (his first full week away) and he was fabulous - lay quietly outside the van each day, taking in all the sights and greeting passing people and dogs without any barking. Came with us on outings to villages, pubs and cafes, the beach, etc - he was an absolute star.
Now we're home, and he's suddenly a first class knobhead. Frantically attention seeking, for all the hours he is awake. He is typically walked for 45 mins in the morning and 20 minutes in the evening (mindful of his age, he's still growing), and he gets interaction from us throughout the day including 10 mins "training" most lunchtimes (just standard stuff to keep his training ticking over - sit, down, stay, find the treats, go to your mat, etc etc). He has free access to the garden and can come and go as he pleases, he is allowed anywhere in the house and on the furniture. Just saying. 
Now he is suddenly PESTERING all day long to play. Pushing toys onto our legs, tripping us up, demand barking, whining. We ignore and ignore and reward for a calm settle, but he's up again in seconds and pestering. He can keep it going for hours - yesterday he pestered and fussed for 4 hours before he finally gave in and napped. Then he pestered our visitors and eventually had to be shut in another room (like a time out) for climbing on them.
When ignored he just plays noisily by himself, barking and squealing at his toys and chasing his tail. Today he's had an hours walk this morning (DH got lost), and 20 minutes this evening including 5 mad minutes playing with another dog. I fed him when we got in but he's been galloping around the room wailing and flinging his grunty pig around for the last hour. He just. Won't. Stop.
He's also pissed on the carpet more in the last 48 hours than he has in the last 2 months - we'd 99% cracked it although we have to be watchful if it's raining, he doesn't like peeing in the rain. Since we've been home he is almost freely weeing indoors - earlier he looked DH in the eye and weed on the floor. I am having to physically carry him outside and place him on the grass (the puppy, not DH).
I don't know what's going on with him, he had his moments before but rarely as persistent a pain in the arse as he is just now. Is it hormonal, will it pass? He has a retained testicle so he'll have to have an op anyway, but not until 12 months to ensure he has all the testosterone he needs for his growth.
No doubt it's us inadvertently reinforcing some behaviour somewhere...he is on 2 meals a day of Wellness Core puppy kibble with some vegetables.