Suffer from ddd in low back. i took a walk around the neighbourhood on sun. now in severe pain. no wrong steps during walk. what could be causing pain?

Lower back discs: If you have low back pain from disc causes, simple activities of daily living may cause symptomatic exacerbations. You should avoid bedrest greater than 2 days and attempt resumption of your usual lifestyle as you are able. If symptoms persist or worsen, further medical evaluation is suggested to rule out other potential problems.