My DD had Severs as well. Said it hurt a lot when running.
Doctor said "it'll hurt, but you aren't doing any damage to it. It'll go away".
So my DD played through the pain and it did, in fact, go away. I think her knowing she wasn't doing damage and knowing it would go away helped her mentally. She just did her best to battle through it. Hoping for the best for y'all.
Pediatrics here. Severs is super super common in this age group. Both of my kids had it. Advanced imaging and orthopedics are not usually necessary even for the highest level athletes. It’s very common in clear sports due to some biomechanics issues that cleats create in younger lighter kids. A stretching program is necessary to help work it out. There are KT tape techniques that will help alleviate the in game strain. I personally have found heel cups more helpful than other inserts. Keep her out of cleats as often as possible using turfs and tennis shoes whenever you can. It’s a growing kid thing and it will get better as her growth slows down as long as she takes care of it.
My son is 14 and has Severs. Told he will probably be 17 before he is completely over it due to the growth plates being so open. He does daily stretches that have helped tremendously. Was told to walk bare foot as much as possible. He started lifting weights and really concentrated on the Achilles during squats while wearing zero shoes (No heel). NB cleats work for him the best.