IT Band Issues. Shoes and pronation?

I would rest that IT band for a solid couple weeks then start out slow.  Like others said you need to strengthen that core and other muscles.  Take the couple weeks off and hit the gym.  Last winter I developed ITBS in my right leg.  I rolled the heck out of it and also worked on more core for a couple weeks and, the problem went away.  I would also concur that your' running form has something probably wrong with it at well.  I'm a believer in the whole minimalist shoe wave and run in Newton gravity's.  Shoes are not always a "Band-Aid" but they can help somewhat if you take the time to learn a better form of running.  Ever since I went minimalist and got way from the "cushy" shoes and big drops my problems have disappeared...(knock on wood)  Newton Motions are suppose to help with bad pronator's.  Personally whenever I am running I am thinking about my form a lot.  I try and keep good form and run mid to forefoot landing.  Granted probably today when I go run 20 miles once it warms up at mile 16 or so I could slack a little in the "form" department.  :P

This is the route I go. 

I don't even believe you can actually "stretch" the IT band, so your time is better spent on a little preventative strength (emphasizing outside leg/hip and glute strength.) 

Thanks all for your thoughts.  Here's what I've learned:

1.  IT Bands don't stretch.  I'm gonna' keep rolling the heck out of it anyway.  I've been told that rolling the muscles around the band helps

2.  running Form:  My running form is pretty good.  high cadence (180) and I keep my feet under me.  I don't think that's the issue for me.

3.  shoes:  probably not it.  I tried running on differently canted surfaces this morning- and it didn't make a difference.

4.  Strength training:  Ahh, the solution to all running injuries.  Can't hurt.  I'll up my routine.  That said- why, after years of running and never having this injury, did it suddenly crop up.  ??? did I get weaker?

5.  Rest:  I'm a firm believer that 98.3% of all running injuries get better with rest.  That said- I've never had chronic IT band injuries, and the only time that they give me a hassle is the first week of running after a layoff.  So- for me, it seems to be related to NOT regularly using them.  In this case, I took 2 weeks off (due to a back injury) and then went out and attempted to run a 50 mi race.  (got 33mi into it and dropped due to hypothermia- but that's a different story, I was sufficiently trained for it and doing well).  I'm going to give it another week of running without ramping up the miles, and then rest it for 5 days or so- see if it gets any better.  

So yeah, as I understand it, you can actually lose some strength/power when you train for distance. You become very efficient at one thing, but the others slip a little. Which is why the supplemental strength plays a role for those opposite muscle groups.

As for why this snuck up now? That's pretty hard to say. Are you saying you didn't run at all for 2 weeks and then attempted to run 50 miles? That very well could be the reason. I think the most common reasons are too much too soon and too fast too soon. Basically any training stress applied too drastically.