2 days ago my 8 year old yellow lab mix became hesitant to walk up stairs. We had finished a walk earlier in the morning, and Chad had no noticeable problem. My house has a deck with stairs (about 8) from one deck to the other. Chad kept putting one foot on the stair, then removing it. He has no problem walking down.
He tried to jump on the bed, but failed, and this from a dog that can gracefully jump on to anything just the day before. I think he might have hurt his front leg, but I don't feel any swelling. He does get rigid when I probe under this front legs, but doesn't yelp. Should I just let him rest, or is this a symptom of something more serious.

Thank you for your time