baby keeps falling

Okay so my son is 8 months. He has been sleep trained but is regressing. I practice timed crying, my main goal is for him to fall asleep in his crib always. Ever since he started pulling himself up, he does that in his crib when he wakes. So I'll be waiting for him to fall back asleep (he never cries for long and can self soothe pretty well) but now he falls in his crib!!!! I think he slides down basically but you still hear it and jump outa bed and he is crying so I of course pick him up and comfort him... this keeps happening. He falls in his crib at least once a night... he doesn't have bruises and is fine once I comfort him. I hate this! What can I do... I seriously feel awful, I never want him to hurt. I am at a complete loss. We have a mesh liner on his crib and he is still in our room.