What the heck is this???

I’m panicking help me me figure out what the heck is this white thingy swimming in my tank

It looks like a detritus worms. No big deal. It won’t hurt your fish. They are in most substrates but come out when fish are over fed. Cut back a little on your food and they’ll go back down. You can vacuum your substrate some too to help control them.

Pretty much as Deanasue said. Do a 75% water change and gravel clean the substrate every day for a week and you won't see it again unless the gravel gets dirty.
Make sure any new water is free of chlorine/ chloramine before it's added to the tank.