Typically figs are not poisonous to dogs, the biggest danger they pose is usually just being so sweet that the dog eats too many of them and ends up with diarrhea and an upset stomach.
That being said, however, there is always the chance that your dog could be allergic to the figs or could be having a reaction to something that was on the figs (such as pesticide or fertilizer). I am concered about his increased rate of breathing, and the fact that his stomach is 'hard'. These could be signs of a possible obstruction from eating the figs and then having some get stuck in the intestinal tract.
My suggestion is to have a vet take a look at him. If this is something as simple as an allergic reaction or something more serious like an obstruction, either way a vet should take a look at your guy to make sure he's not in any danger.
I hope this helps.