I’m afraid the only answer to this one is patience - if there’s no evidence to diagnose, you can’t be diagnosed. I’m sure, as a medical student yourself, you appreciate this.
“Dye”, as you call it - properly called “contrast”, as it’s not a colour - is no help at all in finding lesions that can’t otherwise be seen. It’s only useful in distinguishing between active and historic lesions - i.e. as a measure of disease activity. But for that to be worthwhile, there have to be some lesions to see in the first place. If there aren’t, contrast won’t miraculously reveal any.
Similarly, it is most unlikely to have spinal cord lesions without any at all in the brain. The brain is usually chosen as the most productive place to look, because that is the site that is attacked the most, and also because lesions there tend to show up better.
I was unusual in having a spinal MRI first, but that was only because the problem was expected to be a slipped disc. Spinal cord lesions can present very ambiguously - mine was almost missed - so that’s another reason the brain is the preferred search site. Lesions there tend to be more distinct, and therefore more conclusive.
So what I’m saying is the scan you’ve already had seems appropriate, and is normal procedure where MS is suspected. It’s unlikely that either a spinal MRI or the addition of contrast would yield any additional information, if no brain abnormality was found.
What is the arrangement currently? Presumably, you haven’t been discharged, so are they going to keep you on the books and scan again, either after a fixed period (usually six months), or if there are any changes in symptoms?
I understand your frustration, but diagnosing problems like this can be a very long and slow process of evidence gathering. Obviously, there are risks associated with diagnosing on too little evidence, and getting it wrong, as you may be treated for a disease you don’t have. The treatments are non-trivial, and have both risks and side-effects, so it’s not OK to prescribe them to patients who may not have MS. By treatments, I mean the disease modifying drugs, or DMDs. It is perfectly acceptable to treat symptoms without a firm diagnosis - and a proactive doctor should - hence trying the leveteracitam and clonazepam.
I don’t want to be a prophetess of doom, but I do think it’s in your own interests to investigate what other career options may be open to you, that would use your interests and knowledge, but not place you in an operating theatre. It says it all that your colleagues are already expressing concern. I’m sure they’re not just being nasty, as safety obviously has to be paramount.
Your condition may be fixable, but I’m rather inclined to suspect not - even if it’s not MS. For this reason, I think the more practical and adaptable you can be about your aspirations, the better things will go for you. It certainly wouldn’t hurt to be doing some lateral thinking now, about what other paths may be open to you. You wouldn’t be the first person who’s had to change direction in life, for health or other reasons. What advisory, administrative or regulatory roles might be open to someone with your background?
I am guessing not 100% of trainee surgeons go on to practise in any event. What do the rest do? That might give you an insight into opportunities you might not have thought about. Does your medical school have an alumni association, or something like that, where you could find out what others went on to do? Is there a careers service? Possibly not, if the assumption is that everyone there wants to go on to practise, but as I say, it’s unlikely there is 100% conversion rate anyway, so they must have some idea what else is out there.
I’m not suggesting you should just give up your dreams, but a prudent person should consider all their options - not just the obvious ones. Keep hoping for the best, but prepare for the worst - a good backup plan never hurt.
And answers do come eventually, but just not on demand, I’m afraid. I’m quite certain I’d been ill for at least six years before diagnosis, and sometimes I think as many as 20. I’m not suggesting that would happen to you, as a lot of it was my own silly fault for ignoring what my body was trying to tell me, and not seeing a doctor. But even once I did see a doctor, it was a long time (years) before I found out what the trouble was. I’d been told everything from “silly shoes”, to “having one leg longer than the other” (which everyone has, a bit). Again, I’m not saying this would happen to you, but until they find the smoking gun (e.g. a brain lesion), it’s all hypothetical.