Reason For falling on face

[pen1217]

My husband, 52 yrs old, no back issues at all, he does have a severe neck problems, he has no symptoms from disc disease He was standing in line at a coffee shop bought the coffee turned to walk and fell on his face, no feeling in his leg at all, no numbness, no pain, he describes it like it wasn't there, when he went to try and get up it took a min to get a feeling back in his leg for him to stand...No symptoms since this happened 2 days ago, I called his doctors office on call doctor said he probably just locked his knee and his leg was numb and he didn't know it, now that's just bs. first of all I have numbness and you know when its numb all kinds of creepy crawley feelings. Any Ideas what this could be? He did last week start a sleep drug clonazepam for a severe body movement when trying to go to sleep the doctors don't have a reason for this seen a neurologist and he thinks its his ssri he is on, I doubt that since he has been on ssri for 20 yrs no effects ever from them.