That's tough, sorry you're going through it. I don't know that there is a cure all for such a thing. Depends, I imagine, on what the problem is. Not too long ago I had a similar situation. I woke up one night with my heart skipping and losing my breath. It scared the living hell out of me. I was convinced I was having heart problems. Went to the doctor, had an EKG, had to wear a heart holster (portable heart monitor) for 24 hours and then wait for results. I had to wait 3 days. It was probably the most nerve racking, stressful, terrifying 3 days in my life. All the while all I could think about was what if I have a bad heart? What if I have an artery blockage? Will I need surgery? What if it's really serious and I don't have much longer to live? I couldn't sleep, had trouble concentrating on work, and family told me I was "not the same." So it was obviously effecting me. Not knowing was driving me crazy. I felt like I didn't have control and I didn't know which direction to go, or what to do. Turns out I was just having anxiety attacks....which me thinking I was having heart problems was just making it worse. Once I knew what was going on things fell back into place and I pulled out of my funk. I really think that if I hadn't had family, friends, and especially my wife to lean on during that I would have been in way worse shape. Talking to them helped me relax...at least for awhile.
So if you have someone to talk to, try that. It's cliched, but talking does help. If you're trying to figure out a problem, sometimes people can provide solutions...or at least allow you to bounce ideas off of. At the very least, you'll get some support with whatever you are going through. I don't know that I've been much help, but there it is.