I need your help!!!

Question
I adopted a puppy that now is 1 year and 5 months old, he's a combination of a border collie and a chow chow.  We adore our dog and I worry that something might be wrong with him.  Yesterday, he wanted to be outside on the porch but when it was time for him to come in (since I had to go to college) he didn't want to come in.  Therefore, after several tries I gave up and let him outside, even though I didn't want to because it was very windy.  After I got home (after 5 hours), he came in and has been acting strangely. He seems to be scared of many things now, and his breathing doesn't seem normal.  Yesterday, he push the gate in desperation and went upstairs.  I let him sleep in my room, which has never happened before.  What's wrong with him?  It's like I got a new dog, he doesn't listen to me or my family, and he seems a little scared of everyone.

Answer
This dog is quite young for a neurological insult (stroke), but he appears to be exhibiting signs of high anxiety that might be attributable to many neurological problems: seizures (he's at the age where these appear and they can be quite difficult to diagnose), thyroid disorder, brain lesion (rare at this age), and also very susceptible to the possibility of orthopedic problems (which can have sporadic presentation and be quite painful.)  You need to make an appointment with the veterinarian ASAP!  Have a urinalysis (for white blood count, crystals, etc.), a full blood chemistry (have thyroid checked, cbc, etc.) and a careful orthopedic evaluation.  It's possible this is as simple as an orthopedic injury (common and you wouldn't have seen it happen) that's causing the dog pain (dogs react to pain in alarming ways sometimes, fear behavior being one of them) or has another physical problem. RULE OUT INJURY OR ILLNESS.  Repost if nothing abnormal is found and we will proceed from there.  MEANWHILE, don't attempt to 'comfort' the dog when he is in this state (as he will construe it as reward) but DO allow him to sleep in your room and remain as close to you as possible; put a lightweight leash on him (very short nylon) that you can use to lead him indoors, should he refuse to return inside, because if he has an orthopedic problem the damp and cold will worsen it.  KEEP A JOURNAL of his behavior, both for the veterinarian and for me (should it turn out this is purely behavioral), be your own detective and be as thorough as possible.