Uff, tough news
I went through this in 2017.
As understand it, this can be serious injury than can become chronic and even debalitating, causing the arch to collapse if it stretches or ruptures. Lots of horror stories out there
After a month or so of escalating pain with no relief, I went to a good physical therapist, who diagnosed the underlying bio mechanical weakness, which for me was lack of mobility in the ankles and hips, and very week hips. I did a 2 month period of what I saw as acute interventions to get the injury under control — daily stretching, daily strengthening, twice daily icing. I did minimal running during that period, I could go about 4 miles before I felt it, so I didn’t go further than that. I also got insoles for my running shoes and work shoes
After about two months of that acute intervention, the pain started reducing, so I was able to ramp up running but still maintained the strength and mobility routine.
To this day, I still focus on strength and mobility, along with running and hiking. And if I feel any tweaks in the area I back off and double down on the stretching and stuff.
It’s manageable but can be tough. Really poor blood flow to the area, and basically all the lateral force in your moving body has to channel through that tendon.
I would suggest that you go to a good physical therapist, and realize that your plans and goals have been drastically altered, goal #1 has to be healing it up. Good luck! Let me know if you have questions.
edit: I also remember reading (and talking to pt) that, if there is a rupture or long-term dysfunction, surgery can be the answer and surgical outcomes are often not great...often there is a loss of function. Definitely part of what got me really focused on healing it up.