I'm 73. I had a similar reaction after my third lupron injection. Walking was difficult, my hips, knees and ankles were really sore.
I ramped up my yoga exercises to almost daily at home and once to twice a week in a studio. Yoga is the best. I also started back in the gym lifting weights. It is helping but you can easily overdo it so the initial startup has to be gradual. I have learned that you have to physically fight the loss of testosterone. Yoga is my main go to remedy.