Thanks everyone for your help. I will next time avoid heat and be careful with the cheese I use. I tasted the lump i pulled out. It had the consistency and the taste of salty fresh mozzarella.
Maybe the heat? I was making up a shrimp pasta.
Sauteed Shrimp removed from pan.
Poured off most of the oil added Garlic.
added 1cup cream 1 cup skim milk as it was cooking down added zest of one lemon and juice of half a lemon, Oregano, basil.
Added one half cup of parm. sauce thickened nicely...
Had a great tasting sauce last night and then added some diced tomatoes and the grated Parmesan in sauce turned into one lump that look like fresh mozzarella. removed lump and added more parm. same result. What went wrong?