What to do about an acute, severe muscle spasm brought on by physical movement?

I’ve been doing well with my EMDR therapy and can feel progress with some lessening pain days. I have not returned to exercise (like short walks or anything) in many years, except for swimming about 3 times a week. Yesterday, I felt motivated to clean out some cluttered spaces in my home. I was really absorbed in it and ignored my usual, everyday symptoms. I was definitely doing a lot more bending down and lifting of things than I normally do. I was so absorbed in it (and feeling good about making progress on clutter!) that I really lost track of time and worked physically much longer than I’m used to. By the end of the day, my usual tightness/tension in my back was so heightened that I finished up and sat down to rest. When I stood up, I had a severe spasm in my lower back. This morning, I’m pretty miserable.

Advice on the forum seems to be to take it easy for a few days, try your best at self-care and see if you can make any connections psychologically to when it came on. I’ve done this with severe spasms in years past. But I always feel like they have caused me to setback even more (over time). Sleeping was really difficult with the pain and anxiety over it last night, and I even had a dream about getting X-rays and MRIs (so I know that my subC is still trying to get me to find something wrong or somehow fix it physically).

Any tips on getting through a spasm like this? I can’t connect it to a specific emotional thing. I think it was my fear of physical movement – like, “uh-oh, you did too much and now look what happened”. Or, there is some normal soreness that would happen to anyone who hasn’t exercised in years, but my brain is triggered to heighten the sensations of it. I know that Steve Ozanich pushed through and exercised anyway, but I don’t think I can do that.