panick attacks

Question
I have recently rescued a staffordshire bull terrier from a crazy woman that was beating him in public. He is an older dog, about 7, and despite his hatred for cats, he is a relatively calm, loving good dog. Lately, within the past 3 days he has been having "freak outs" when on his walks. He will lash around like a fish on a line (best way to describe it) and then he will try to chew or climb anything he can get to, for example he attacked a fire hydrant and was chewing on it so violently I thought his teeth would fall out, on another walk he attacked and tried to climb a sign post, and on another walk while bringing him back in the house he started lashing around and climbing, a squirted him w/ a water bottle that calmed him down temporarily until I walked in front of him and he grasped around my leg with his front legs and put his head between my thighs and started thrashing his head against him. he has had formal training when I first rescued him, and he normally minds very well, but I am not sure if I should bring him to a trainer or a vet for this problem. Do you have any idea what may be causing this reaction? Or if I should take him to a vet or trainer? Thank you in advance for any advice

Answer
Lyris,
I think you need both a trainer and a vet.  I think you should put him on prozac, but check with your vet.  He also needs to be checked for a brain tumor (just as a precaution)  I dont think he has one, but it would be good to get an Xray anyway.    
Also get him the pheromone collars which calms a nervous dog.
You might want to get him to a behaviorist.  She might be able to see his actions first hand and be able to help you with this  problem.  It sounds like anxiety from his upbringing...Dogs can change, so keep being hopeful and consistant.
nancy