That's great to hear that your wife is doing so well!
Actually, to my knowledge and experience, since a definite diagnosis of MS is so difficult to obtain in the first place (MS is hard to find and doctors do NOT diagnose someone with MS quickly at all), and your wife was put on injectables, I'd have to suspect she was diagnosed with definite MS, which takes quite a bit of unrefutable evidence before that diagnosis will be given in the first place.
Yes, there are many diseases that may mimic MS and vice versa, but an MS diagnosis is only given out when all other possibles have been tested for and ruled out, and even then there's an extreme hesitancy from the medical field to diagnose a person with MS. Especially since there is no one conclusive test that tells the doctors that yes, you have definite MS. There are different levels of MS diagnosis, also. They might start out saying "possible MS", then they might go up one more step and say "probable MS", and the very LAST diagnosis they hand out is "definite MS". That isn't diagnosed easily or lightly at all.
Is it "possible" that someone could be misdiagnosed with MS and immediately placed on injectables? Yes, but very highly unlikely. Some people struggle for many years trying to get a definite diagnosis even when MS is "suspected".
It is a well known observation that during pregnancy, MS remits, and only tends to return after the pregnancy has ended. The supposition is because a woman's hormones change drastically (to avoid the body's automatic rejection of foreign matter) in order to avoid miscarriage.
Levels of certain substances (that make up the immune system) change during pregnancy, which provides protection for the fetus, and in doing so, also provides some relief and remission of MS. After pregnancy, a woman's hormones and immune system return back to the levels they were at before pregnancy. Hence the reappearance (most often) of MS symptoms.
So......how often is MS diagnosed when it's really something else? Almost nil. MS can be misdiagnosed to be something else, though, (when it's really MS and they didn't find it or diagnose it correctly).
Frankly, I would personally advise you to continue to research as much as you can about MS itself and how she can help herself with the proper medication (as she apparently is currently), diet, exercise, etc. etc. I truly believe it would be a waste of valuable time and effort to try to pursue the misdiagnosis angle.
I hope I haven't been too blunt. But, remember, don't freak over MS. It has become more manageable in recent years, and hopefully will continue rapidly to be even more effectively treatable in the near future than it is now. The future looks bright!!!
I've had MS since practically birth, and I'm still doing real well. I had three children, and currently have 4 grandchildren with another on the way. You'd never know that I've had MS for 49 years! So, keep your chin up. MS is not necessarily always a "sentence". Try to remember that as often as you can.
Nice to meet you. And you sound like a wonderful family!!
Best to you all,