I Have Taken Tenex For Years But Recently Ran Out

I have taken tenex for years but recently ran out them and was out several days before a refill. I have episodes that cause me to fall after getting up from sitting and taking a few steps. It feels like my neck and head are in a vice and if I don't sit quickly, I lose control of my extremities in a jerking motion and fall. My last fall resulted n two dc' s in my femur requiring surgery. I have noticed that I have not had these episodes since I didn't get a refill in the mail for a few days. Could the tenex have been the cause? Thank you in advance.