Anxiety?

Are you sure there haven't been any changes in your home at all, like routine, or maybe a change between the dogs?
Dogs pick up on the smallest change, even if it is something small going on with you.

Is the dog crate trained? Most dogs benefit from having a crate to crawl into, call it their save place.

Do the dogs get the same amount of exercise?
When winter hits and dogs get less exercise due to cold weather they seem to get more tense.

Oh Annie, when you say randomly licking, how often and when. If it were an obsessive type thing I think he would pick on spot and focus on that, could he have gotten some kind of chemical, like fertilizer or something in that area?
The shivering really bothers me. While dogs do shiver when they are scared, you can usually spot the thing thats scaring them, like thunder, vet. But shivering for no outside reason, could be pain, or fever, or  dehydration.

Karyn, the only thing that is mildly different in the house is that it's getting cleaner. ~L~  I have also tried to treat both dogs the same.  I was having some issues with Grady. It was brought to my attention that there was some inequity in how I treated them & Grady was not pleased.  He was peeing in Aspen's food bowl.  He has pretty good accuracy too.  So I've been trying to treat them more equal.  Grady's peeing stopped.  I try to do some degree of NILIF with both boys.  Also I was going through kind of an emotional time.
Aspen used to have a crate but it was where he was kept most of the time & it's not a good place for him & he's let us know that in no uncertain terms.
As far as exercize is going, they're getting more.  We recently had our back yard fenced in.  Both boys run all over the place.  It's so much fun to watch.

Deb, the paw licking is one thing that I'm sure with some changes I can help.  We do not use any fertilizers on our lawn (that's why it looks so cruddy).  As far as any other chemicals touching Aspen not possible.   That would mean I'm cleaning the house & that just isn't happening yet. ~L~  I'm really not too too concerned about his paw licking.  BTW, he's licking both front paws & one "wrist".  It's the shaking or shivering that really has me concerned.  He was @ the vet yesterday for his check-up & all seemed fine so that leads me to think that it also is behavioral.  Maybe he's missing seeing people like when I took him to see dad, I don't know.  He really seems to thrive when he's with people.
 
Edited: for grammar changes

Ya, know Annie the fenced yard, and all that freedom, may have scared him, kinda like someone from a Communist country coming here, we think they will love it but it's sometimes too much freedom, and decision making for them and they get scared. Maybe hang out there w/ them a little show him no monsters out there. I don't really know just keep an eye on him you know your dog.

Deb, you may be onto something there as far as the shaking goes.  Now that I think of it the dynamics of their play has changed outside.  In the past when they were on tie-outs & I let one dog in the one that was inside would immediately "attack" the one entering the house.  Attack meaning that they would play jump on the entering dog & try & initiate play.  Now that they are outside Grady is the one who seems to be all over Aspen.  He#%92s not playing down to Aspen like he does inside.  You#%92re probably right that Grady#%92s play style outside is scaring Aspen.  Thank YOU for the insight.