thank you for your thought out response.
yeah, hyperextension feels right. can't imagine anything is broken, doesn't hurt THAT much.
i went to training and taped three toes together, worked pretty well, no severe pain.
it was my foot on the mat which took the hits though, not my kicking foot.
it somehow got "stuck" on the mat when i turned in, so basicly it was twisted back towards the heel.
after that it happened 4-5 times over.
anyway, tape seems to be the solution, thank you!