At my wits end with a baby that won't sleep. Any suggestions?

I know that this question has been asked countless times before, but I need to ask it with my own circumstances inserted. I have a 15 week old son. He has acid reflux that is being treated. Ever since we brought him home, he has had trouble sleeping at night. It made sense in the beginning. I think that the whole time that he has been home, we have had only a couple of good nights. For the past 4 days, he has been awake from 2am until after 10am. The worst possible time for a baby to be awake. I have tried everything that I can possibly think of. I swaddle him, I don't swaddle him, I let him sleep as much as he can during the day (to prevent him being overtired), I keep him awake most of the day, I rock him, I put him in his swing, I switched him to formula (because it takes longer to digest), I let him cry for awhile, I try to soothe him when he cries. Nothing seems to work and mommy and daddy are very exhausted and can't do this anymore. We also have a four-year-old daughter that is being affected because I am just so tired during the day that I can't interact with her the way I want to. I am easily agitated and aggravated. I just need some help and this is like a last resort at this point. His pediatrician gave us the book "Healthy Sleep Habits, Happy Child" and left it at that. It's not really helping. I have a feeling that I'm not going to get much because I feel like I've tried everything, but I thought I would give it a shot. Thanks in advance for any suggestions that you may have.