For some reason my second reply wasn't posted.
I measured the current between the input and the resistor and it was slightly above 1.5v. I replaced the resistor for a 1k resistor and everything works well now. I thought that a higher resistor would limit the current much more than a lower resistor, but i probably didn't take into consideration the "direction" of the current. Thankfully it's been solved.
Thank you very much, everyone. I learned a lot!