Don’t try running if it is causing you pain. You won’t loose too much fitness if you cross train consistently (biking, swimming, rowing machine, aqua jogging if you can, etc.)
I don’t know if you do any of these or not, but make sure you are stretching daily, if not multiple times a day. If you have access to a foam roller, learn how to use it correctly and be consistent. Kt tape can make a good difference. As someone who dealt with peroneal pain, I can say that kt tape made the difference between not being able to run at all, and being able to train at full capacity (alongside keeping up with the other stuff)
Here’s a tutorial I used for taping the peroneal:
Sports massages can make a huge difference. I would definitely recommend getting one.
It’s only the start of August, don’t get too discouraged. The cross country season is long, depending on what state you are from you have 3 to 5 more months. I had a teammate that had a bad injury near the start of August, cross trained for about a month and a half, and still ran at the state meet running a pr.
And if it doesn’t work out, I have learned when going through trails to look to Jesus Christ for comfort. He suffered your afflictions that He might know how to heal you. Turn to Him.