Its really tough to keep your temper in check with those rascals, but you just have to do it or possibly risk completely losing him. Probably a good idea to take a little break and just be his pal for a few days. Are you training by any particular book or regimented system? I have used (and so have a lot of people over the years) "Water Dog". It's an old book but has been used successfully for many years. Keep your cool with him, he'll come around.