If you go to a half decent physio they should be able to feel if it is bad Tendonitis or not.
If it is Tendonitis the only real resolution is rest (depending on severity). Massage and stretching all help, again dependent on severity.
And sort your cleats, no need to pay someone to do that for you.
6 weeks rest later and was out at the weekend, another big ride stupidly though I feel like I’m back to square one.
This is your problem too. You should have started with 5 miles and see if that caused any problems. If not increase by 10% each ride.
I am just recovering from an ankle Tendonitis problem, I tried the short period of rest followed by back to normal (the experts told me not to) now 9 months later I am just back to exercise and building back up the mileage.
Don’t be daft and wreck your future.