It sounds as though you've not got yourself into too much trouble yet, so be sensible, take a few days rest and take some time to learn about what causes the IT band issues. I found the blog linked below a really good resource for understanding the physiology of it, but didn't find that particular stretch to help too much. Have a look on YouTube and find something that works for you, I've linked the one below that I use regularly. The exercises mentioned above are all good advice, but I'd say pick one or two of them and do them properly. It's all too easy to do them with rubbish form and not target the muscles you're supposed to be targeting, again look them up on YouTube and follow their advice on proper form (link for clamshells included below).
If you can bike and swim without it flaring up or giving you issues afterwards then go for it. This will depend heavily on (1) how bad it is at the moment (2) your kicking/pedalling style and (3) how hard you push it, so there's not really a set yes or no answer. Listen to your body.
When you think you're ready to run again, keep it short and slow. I can't stress this enough, just completely forget what distances and paces you were doing before, start fresh. If you can only do a mile or two, then start with that and build it up from there. I was told by someone else that a good motto whilst rehabbing yourself from injury was to "quit whilst you're ahead". I didn't like it because it sounds very negative and defeatist, but in my experience, it's good advice. Going out and trying to run 10 or 15k isn't going to help your fitness if it's not sustainable; getting in a 5k and calling it a day before your knee flares up is going to be more beneficial in the long run.
Good luck and have a look at these: