I've been running for the past five or so weeks, and have gone on a couple long (for me: 10k) runs in the last 2 weeks. I developed a pain on the inside of my left ankle (non-dominant) that sometimes reaches up into my lower calf. It seems to be especially painful while pronating and pushing off. I probably pushed too hard on my last run, so I'll slow down in training for a while to build strength. But what muscle or tendon is that? And is there any other strengthening exercises to help it out?
The posterior tibialis controls pronation but the actual “foot roll” comes at the end of a very long kinetic chain. Each running step is initiated (or should be) in the glute and travels through the leg. The pronation could be caused by any sequence of weaknesses in the kinetic chain.
For many runners (and non-runners), weak glutes can cause a plethora of problems people wouldn’t normally associate with a weak butt.
If you went from zero to 10 km in 3-4 weeks (?) , your problem might also be caused by overload. I'm not a doctor, but... a very, very common overload problem if you start out too aggressive with running, is Plantar Fasciitis, which more or less match your description.
Google it - there are plenty of good articles on this subject as it is so common. The cure? Usually, you just have to turn down the running a bit when you discover it soon. There are also some good exercises that can help you getting over the injuries faster.