Night Shift is killing me!

Hello! I have been an RN for about 6 months now and have been working nights for 4 months. I actually like my current job for the most part although it is VERY stressful at times. My problem is I absolutely hate night shift. I work three night shifts a week but I feel like I work 7 days a week because I can never recover! I am constantly tired and cranky. I have gained 20 pounds since starting night shift and have started to take blood pressure medicine. Sometimes on my way home I will literally doze off and drive off the road, scary. I just can't adjust and I've tried EVERYTHING! I have talked to my manager about my problems and she said it will be another 6 months before I can move to days. This seems like too long with the way things have been going. I don't want to leave my job, but I feel it has started to affect my health and well-being, and it's kind of a safety issue sometimes too! There is a doctor's office RN job 10 minutes from where I live. It is a 9-5 job which is a lot different from what I have been doing but I'm thinking about it. I applied and got called for an interview, and was offered the job. I really am having a hard time deciding what to do. This new job will have great hours and be close to home but is not in a specialty I am particularly interested in. BUT, I don't think I can tolerate night shift for one more week let alone 6 months! Any advice?