i found a thin long black thing that looked like a worm in my semen after I felt testicular pain

Yesterday I got really bad testicular pain, like really bad, I told nobody as it started happening around 5pm and I was in my bedroom it disappeared today, this is where it gets weird, I masturbate once or twice a day, so I masterbated fine yeah, 5 hours later I go again, but this time was weird, when I cummed my penis flinched(this never happened before) so I sit up to clean up and I found the weirdest thing inside the cum, a fairly thin long black thing that looked like a worm, I got super nervous as I thought I saw it move but turns out it was a string, how did that get in my testicals? Should I be worried?