exercise to replace running

i have been diagnosed with iliotibial band syndrome. i went through PT and had some success, but the pain reoccurs regularly despite the fact that i still do my stretches before and after running or walking and i wear orthodics. i tried alternating running & walking every other day, but the pain still comes and i don't feel like i am getting a great workout when i walk. is roller blading a viable alternative for me? i have heard that cyclists can get the itb syndrome, too, so that doesn't sound like a good option for me. i must exercise! what can i do?