Pregnant and constantly tired !! Help

I'm pregnant with my second child and I do not remember being this tired ever! My DH has been amazing about taking care of our son and letting me go to bed early and sleep in etc.. I get plenty of sleep every night and sometimes even naps. It's not like your normal fatigue and sleepiness. It's awful.. I can't even hardly stay up at work or just doing normal everyday things. Is there anything you ladies can recommend?! I'm not sure what else to do.