Pain and burning in stomach is not due to exercise.
I will advise you to take plenty of water during exercise but not at once.
the burning in urination may be possible due to urinary track infaction in the case of chronic urinary track infection uretrosis may be develop that cause may be also lower abdominal pain
presently you should stop the excrise because in this condition you will not feeling better and it may be harmful also . you should consult medical medical specilist