Ankle stretching burning sensation

[Horrible Joke]

I'm trying to improve ankle flexibility, but when dorsiflexing, I don't feel any stretch at the back of my ankle, just a burning sensation at the front where the muscles contract(the kind you get when muscles are being worked hard). I used to think this was normal, but upon doing research I see no one else mentioning it and I don't imagine a stretch is supposed to feel this way.

My concern about this is mainly that I'm worried it will limit my ankle flexibility. So is this normal, does it mean my ankles are getting flexed as hard as they ever will be, can flexibility still be improved or is this not supposed to happen at all?

Thanks in advance guys