Back of right knee hurting. Been going on for several weeks. Tonight, almost fell, can t put any weight on it. Luckly my wife had a walker from previous knee replacement, but still very difficult. Lying down with ice on back of knee, taken aleve, elevated. Should I call ambulance to take me to hospital or wait until morning? I a m 70 yrs, over weight, sternts in heart , other health problems. Right now I can t even get to