For pizza red sauce you need fresh tomatoes. Put the tomatoes into hot water to peel them,If you don't like the seeds, remove them.  after cut into the small pieces or squeeze  the tomatoes with your hands. try to remove the juice in excess. Now the sauce is ready.
As for the problem with your pizza dough is too much difficult to answer what it the real cause. It depends on the type of flour you use,the fermentation, the temperature of the dough, the proportion of ingredients in your dough and so on.