Transferring of impurity

Dear brother i have ocd and every time i want to pray i get a doubt that some thing is najis. Please brother few of my question might be silly but very important for me.

The other day i scrathed under my bowel and my dirt fell on carpet. Does it become najis. If yes i pour water into my hand and splash on the carpet and i think cover the area where the dirt was.

Also the other day i took a shower and didnt do istinja and i wore new clothes i saw some feaces in my clothes i wash of my clothes does where i sat became najis.

Sometimes when i wake up my underwear feels cold should i consider that as urine. Also when changing clothes it touched my feet and i doubt that my feet became najis. Should i wash them.

Also if your hands are najis and you touch the phone while hands are wet does phone became najis. If yes how to clean it.