My dog is acting strange

[angelfin]

My dog has been acting Very strange as of the past few days. He has never been the type to want to be picked up, and would usually growl or snarl at whoever would try. But ever since 2 or 3 days ago, he'll climb up onto peoples laps without being told to (very unusual for him) and he would shake as if something had scared him. If a closet door is opened, he'll walk in, and it takes forever to convince him to come out. He follows people around so he's never alone in a room, which he used to seem fine with. He'll even follow me into the bathroom while I brush my teeth.
My mom suggested that maybe he had abandonment issues, but he's rarely ever alone at home. My grandfather lives with us, and he seems to be the person that the dog favors anyway, because he follows him the most from what it looks like. At first I thought that maybe there was a bear or other animal in the bush behind the house that had spooked him, but we've had them before, and he would usually bark rather than become frightened.
Any ideas what might be wrong with him?

[homerunsally]

I personally would always check things out with my vet first. If all is well there then you need to figure out his behavior for yourself. Put him on a leash, take him different places, and observe him very carefully. See if he is more resistant in different areas or situations. Even if your behavior is causing him to react differently. For example, my dogs know that when I shower I'm leaving the house and they get excited thinking that they might be able to go with me. If so perhaps seek some advice from your vet, a professional trainer, or a behaviorist. Now you will be armed with more info about your dog.

[zoe114]

I hope you will get bloodwork done for your dog. I have found with many pets I have had over the years that when they were acting different that they were ill.  
One recent dog started being more agressive with the other two dogs and I thought it was so odd as he is a very kind sweet dog. After I noticed this agression, he had a seizure. I called several vets, one suggested I get bloodwork, Chem and Thyroid testing done. He said that often it's a low thyroid. None suggested I do these test right away, but I did and it did turn out to be a low thyroid. You know your pet better than anyone. If one vet does not listen to you, find one that will. They all are good, but some have seen cases different than others.    

[Poobear222]

Angelfin, check in the news if any natural disasters happened/going to happen sometime soon in the area (your province or surrounding provinces).  Some dogs are extra sensitive and can detect up to a week or so before happens.

But of course, this is further to your checking whether there are any heath issue first.  

[Dan Sims, DVM]

Behavioral problems aside, I would be  concerned  he may have a
back problem,( either a disc or muscular).Discomfort and pain can result in strange behavior
such as you are describing.
Your veterinanian will help figure this out.
When your Veterinarian rules out physical problems then emotional issues can be addressed.
Good luck!