I've just got into this stand up stuff

Gets me off my fat bum for a bit of exercise.
So far only a few paddles on an 11.6 no name entry level board that ticks all the boxes for me so far,flat water lake paddling.Waiting for the big wind swell to try out a bit of surfing.
So after all that the question.
I am experiencing a lot of foot pain,mostly under the instep,kinda like a cramp but more a pressure thing.Anyone got a solution for this?
Deck pad on my board is not a smooth surface but has 1 or 2mm high raised pattern,could this be the prob?