Trouble walking after Foundation Training (24M)

So I’ll preface that I’ve had back pain for the past 4 months, pretty much around the time I gained weight. I work a desk job and my pain is triggered most by sitting. I decided to try Dr. Eric Goodmans foundation training yesterday. While my back felt good and sore for about 30 minutes, I had significant trouble walking for the following 6 hours. I could still walk but I was very stiff and hardly felt like I could stand. I felt very normal this morning, tried the workout again, and I am once again hardly able to stand/walk. I know my dad has spinal stenosis and he lost the ability to walk at 60, so I fear for my own future as well. Any help is appreciated