Take a deep breath and relax.

Now, try and figure out if your UW scores are too high (are you doing Random timed unused question blocks?) or did something happen to interrupt you during your NBME? (NBME scores too low) I suspect its a combination of both.
You should go back over your NBME results and see if you agree with their assessment of the areas in which you are weak. In any case, go over all the "below average" performance areas and see if you can figure out what went wrong.
Then, I'd finish UW completely and then go over the mistakes you made in UWorld. Make sure you understand the explanation completely for every question - both the ones you got right as well as the ones you got wrong. UW explanations almost always have something to add to your knowledge base, so I'd strongly recommend absorbing that.
After that, pick a whole day that you can dedicate to this and do 3 random timed UW blocks in the morning and then NBME form 6 in the afternoon. That will help you determine your actual score. If it does not substantially improve, you will have to look at going over bigger resources like Kaplan again in order to guarantee a pass. I think you'll be pleasantly surprised though
