Please help, dog hiding, being weird, was panting and shaking -what is wrong!?

very unusual.. One excellent way to look for stress signs and calming signals is to watch dog training "reality" tv shows, with the sound off. Without the interference of the dramatic music and what the host or narrator is telling you, watch on your own to see signs of avoidance, appeasement, and being "shut down" (too intimidated or afraid to show any reaction, catatonic, unreactive). Remember, not all "stress" is distress; some stresses are merely challenges that might even be enjoyed (think of learning something new or playing a challenging game). But if you see multiple stress signs, or if your dog gets "shut down", then the challenges might be too much and these may be warning signs.good luck