Bizarre reaction to MRI?

Here's a weird one.

I had an MRI two days ago, during which I could feel my lateral temple veins throbbing throughout. Also, during the "chig chig chig" part of the scan, a muscle in my lower right back would spasm in time with the scan, and stop as soon as the noise/pulsing was over. (By "chig chig chig" I mean the part that sounds like the broken washing machine, as opposed to the "whir" part of the scan).

In any event, I leave there feeling more or less fine. Perhaps a little dizzy, but nothing to write home about.

That night I go to bed and somewhere in there I woke up and said "I'm sleeping on my right leg in a weird way, I need to turn over" and then did so, and fell back asleep.

When I woke up the next morning -- the day after the MRI -- the upper parts of my right leg were in major pain. I was hobbling all day. I said to my coworker that "if you told me there was a crack in my right leg I would believe you." Going to bed last night was *extremely* uncomfortable. I was finally able to get some rest by elevating the right leg.

This morning it is marginally better but I've notice a swelling in the area of the right leg just under the groin line, on the leg. It's almost a large lump.

I was a runner for many years and I've never experienced anything like this -- how on earth could I have pulled a muscle that severely in my sleep? Could the MRI have provoked something?

I got the MRI to ascertain what is going on with various neuro symptoms (tingling/numbness left side of head/pressure on left eye/light-headedness/cranial pressure).

Sorry for the long post but I thought I'd get it all out there. The leg thing is seriously bizarre.