This is a very dangerous situation. I would do a vet check up to see if the pain in his back legs has gotten so bad that it is causing him distress whenever people are around or if there are other medical problems. If there are no medical problems (and it sounds like a pain issue) then either put a basket muzzle on him until you can sort out the cause or you will likely get bit again. I hope there are no small children in the home. I think if this behavior only began after the moving and plane ride something may have happened during that time as well to change his attitude, but if he was biting before the moving then you have a more serious situation. Either way a behaviorist may be able to help but do get help soon before you get charged with having a dangerous dog.
Snake Vom Eselspfad RN CGC (AKA Raina) 3/5/08
Pyrate CGC 4/1/03-5/16/12 RIP
Too many to list waiting at the bridge but remembering them all