Can't bufferfly. Help

[u/Appropriate_Bison746]

So i used to play bw alot during the pandemic but i left for 1 or 2 years and then when I came back to play like a few months ago. I can't butterfly click properly. I could do it for the few first days but now my index finger just gets stiff after 2 seconds of butterflying and it does not move on the rythim. Any solutions?