I am so sorry to hear about Tubby's walking troubles today.
I can say though from personal experence that my arthritis kicks it in over drive before it rains, during and after. When it snows out, I can feel it really bad. There are days that I don't want to get out of bed because of it. And truth be told I have had a hard time walking because of mine. My knees will go out because they hurt so bad and I can't stand to stand on them. I hope that this is a one or two day thing for Tubby. Good luck with him.