I use to slobber only when I had a cold and couldn't breath trhu my nose. Now I slobber a lot every night. Why is that?

Deviated Septum. You may have a deviated septum that is causing you to drool at night. A deviated septum is when the center part on the inside of your nose is not lined up in the middle. This can cause you to feel like you have a stuffy nose & make it harder to breathe through your nose. Instead you breathe out of your mouth, causing you to drool at night. Snoring is also a sign. It could also be allergies. See dr.
Mouth breather. Many things can cause this but what might be happening is you are now breathing through your mouth while sleeping more often than before. It could be allergy, drug side effects, trauma to mouth or nose, obesity, sleep apnea... Successful treatment depends on finding the cause.