when i press the starter i hear a click which is normal but then the battery vltg drops to like 3v then shoots back up when I take my hand off the switch. also idk if this matters but when i did a vltg drop test from positive terminal to the positive hex key on the starter relay it started clicking rapidly. Is this the battery?

 

yup. battery is toast....

you can try charging it, then have it load tested. if its a few years old, i'd replace it. being stranded with a dead battery is no fun at all.