Hurty back foot

Been mainly on the longboard for last 3 months and seem to be aggravating some deep bruising on the inside of my back foot. Never a problem on my smaller boards, although I have been in the water quite a bit more recently and boots have been off for 3 months. I don’t feel any obvious contact when I’m popping up, but assuming I’m probably dragging it a bit. Anyone else get this? There was an old post from 2012 here but sounded like a different part of the foot.
Apologies for the photo; hope you were not eating whilst reading
Apologies for the photo; hope you were not eating whilst reading
