When is it time to look in to getting a new physician?

I'm really at my wits end. In the last 2 weeks we have been into the ER with my Father-in-Law 3 times for chest pain (directly over his pacemaker, being the worse, radiating down his left arm), very low blood pressure and pulse, and weakness. These are on going ailments. We have talked to his cardiologist multiple times about it and he keeps telling us there's nothing wrong when every other physician we talk to tells us to go back to the cardiologist because it's the heart. Is it time to try a new cardiologist, or are we not asking the right questions or giving the right information, or is he right and it something else no one has figured out yet? I know that many of you are not doctors and can't answer the last question but I guess I'm so lost at this point I just need to say it out loud.