I explain the swelling in an e-mail towards the teacher. I want to be more into technique and training, before I move on with the steps, which I find to be a side-issue at the moment.
That I got 2 mild injuries in 5 lessons is probably a sign that I want to go to fast or do something wrong (well, that's basically the same I think)

Too much practice

And as it turns out, I ám moving to fast to cope with. Besides the stretching done wrong I practice far to often. Daily, I'm trying to get up on my toes and down on my heels again for about 60 times in a row.
This exercise trains the muscles an Irish dancer will need the most. I only do it far to often. Not more than 3 times a week, with a day rest in between training-days.

I get some new moves to practice and at the same time, my left foot starts to cause some trouble. Without me really noticing it, I'm probably being a bit to enthusiastic.
Way high up on my toes as I am, I'm straining everything, especially the muscles in my foot, which causes some pain.

I still lack control over muscles in my feet...

It's something I can hardly change. At this time, I just lack control over my muscles to find a way down the middle between 'As high on your toes as possible' and 'feet flat on the floor'.
My seven also needs a fair bit of work: instead of a fluid motion to the right and left, I have a tendency to step up and down, which isn't supposed to happen.
Even normal walking causes some pain in my foot, so I refrain from practice this week and keep up stretching.