I wouldn't worry so much about the PES status if I were you. Just be aware about the nature of your injury. The army doesn't downgrade you to PES C easily so it should be quite bad. And if it's bad enough for a military post it doesn't work well for a pilot. But as you said it's temporary so it wouldn't be a big deal and you will be upgraded. Unless you know your injury is a bad one, then you are better off consulting a doctor than to ask us.