Really worried advice please,

On holiday whilst on my 2ww thought it was great as could relax and forget the dreaded wait with out peeing on sticks all week, whilst at the beach stupidly (now I realise) I did the ringo rides with my family, huge amounts of bopping up and down and being thrown around, that day (Monday) had bad tummy cramps and AF came very very heavy and very very clotty, still bleeding like this, my AF wasn't due until Thursday...would this of been an early miscarriage? Or could the ride perhaps just bought on my period. In so much pain and AF usually only painful day one then gets lighter, I seem to be getting heavier...thanks in advance xx