First off consult a doctor just as a safety check, as a lot of time the first sign you got of something being wrong shows up when your really working your body. Also a very minor touch of the flu could have did this. I found this out the hard way when one of my clients suddenly dropped their weight and ran over to the trashcan. I sent them home to go see their doctor, and was call later and told they had a mild case of the flu, never got light headed or nauseous again.
Also yes this could be caused by going empty too long and then doing a really tough workout. As in general, most people go a good 10 hours if not more empty by the time they wake up, and then do a workout shower and finally have breakfast. This is nearly half a day with no food. And an intensity change can really make this show up and do a ton of strange things. Also with no food, your stomach might just be too acidic, and with the tougher workout it just can't handle it, and it all comes out.
What differences have you noticed between MM and your other workouts? Any thing in the upper back/neck area getting more worked then you usually do?
Also this can be caused by lifting more then you should in your upper body faster then your body is ready for, you grab those weight and lift them and you tighten your jaw, and tense those neck muscles, you can be tensing a little ear muscle too, which will have the affect, that your having. And I don't mean a weight actually being too heavy, which is a possibility as well for this to happen, but also just your body wasn't warm up enough or was too tense.
These are all questions to think about, and if this continues try to do it later in the day, or less reps, or slower then Cathe. And if that doesn't work it probably your body is out of alignment, and there are exercise(s) that aggravates it, in that particular workout. And that's when it's your call on how to fix it.
Kit