Hi Adam,
Frist, I’m not a medical professional and only share my personal thoughts. This is by no means medical advice – please consult your medical professional for medical advice.
I think the following:
Both, the pain in the hip and ITB can be caused by either overuse or bad posture sometimes both. Hip pain is tricky as it can have several root causes from herniated disc to SI joint to hip itself etc. pp. In order to diagnose the reason for the hip pain, your doctor can do several mobility tests to kind of get an idea what it is.
The IT band goes from your hip down to your knee. It can be caused by running, bad running form, wrong shoes, running on a sloped road, etc.
It could be that one is caused by your running form/shoes/surface and the other from a bad bike fit or both.
My recommendation would be to see a doctor to get a correct diagnosis and then tackle the issue with specific exercises and stretches. You need to find out the reason for your issues – I would look into a bike fitting and running shoes.
Without knowing your athletic history, how much you ran before you started the plan, your weight, height, experience, etc. etc. it is very difficult to help but I feel that should not be done in a forum anyways.
Lastly, and I know this is tough for most athletes (I know what I’m talking about as I cannot run at the moment neither), don’t run until you are pain free and running doesn’t aggravate your injury. Even with cycling, I would be extremely careful as your fit could be a contributor. If you ride, I would not recommend to ride beyond Zone 1 or 2 if you it causes pain/discomfort.
This is not your A race and if you come in a bit flat I wouldn’t worry. If you cannot race at all because you thought you need to push through, you have an issue that will likely also cause you to start your training for your half distance delayed or, worst case, not at all. Be smart, take a break. Don’t risk a severe injury.
Thanks
Winoria