What are Intrusive Thoughts and Are They Normal?

what exactly is the definition of an intrusive thought? I've had some weird ones before, and I don't know if its normal, anxiety, or something else. while getting called upstairs, now my partner is nowhere near mean and has never touched me, but I instantly thought, "hes going to push me down the stairs." last night, tmi, I was laying "in position" on the bed for, yknow.., and he took his phone out to play music like he always has, and I panicked and covered myself so convinced he was trying to take a photo to use against me, or to keep for personal gain. about an hour later before bed, he was scrolling though YouTube to find a video to watch together, and I freaked out and grabbed his phone panicking it was mine and he was looking through my messages (no I have nothing to hide either). its nothing to do with him necessarily, we've always had music and always watch a video so it's "the norm" for these things to happen, so why in the world did I freak out so bad? tbh I've been on Zoloft for a month and I've started getting energetic and irritable for a few days now while feeling pure bliss and euphoria for a month straight with no side effects, sorta panicked haha. thanks.