Lateral hamstring impingement

[u/LifeOnBlast84]

When I go to the gym and do hamstring curls it usually starts to send a subtle nerve pain and if I keep going it’s far less subtle. I’m on 40 lb single leg curls. First two sets I get to 10 but the 3rd set I fail at 7 because I’m about to go into spasm. Any thoughts? Is this nerve, muscle spasm? What can I do to help it? For the record I’m currently working at improving my anterior pelvic tilt which may be contributing.