First, I am going to pray for you that they find out that it is nothing (I know you must be scared and this issue isn't helping any). Second, your husband has obviously done well in the Navy prior to this stressful situation to advance to an Officer Status - does he have anyone that has mentored him (prior to his officer promotion) or recommended him for advancement? If so, maybe that would be a good place to start for getting some advice on how best to handle his situation - not just a day off for you but the change in the stress level for him. I would think that after a career in the Navy, there would be one person that could give him good sound advice and maybe even help him out! God bless you and I hope he works things out at his job - I know how miserable it can be for a family when the husband/man is not happy in his job (believe me I KNOW!).
I too will pray for you and hope all goes well. The Navy is very good when it comes to a medical issue such as yours IF they know the importance and what is going on. Your husband is not telling his next in command or the CO about what is going on at home. And this is common. Not all guys want their business out there for all to know.However, it sounds like he is having a hard time dealing with what you are going through and is using the excuse that he can't get the day off to not deal with it or he is just hoping you will go by yourself because maybe he thinks it's just a test and you can do that on your own. Have a talk with him and let him and ask him why he's put this off and see if it's one of the two i've suggested. Let him know that you really need him to be there and why you need him. If he still gives you a hard time let him know you'll go to the Navy Chaplain and explain all of this to him (the Chaplain)and ask that you will ask him to talk to your command. I suspect he will come home the next day and tell you he will be there for you. Good luck to you and I hope your test goes well.
I am not sure who you could talk to, but I wanted to wish you the best, on your upcoming scan.....God Bless.