I cannot see how this has anything to do with being in pain or CM etc..
I put them both to bed, and 10 minutes later he's freaking out digging his bed, moving the washing basket from the corner, whining and whimpering, and finally just getting in a right state. He ended up covered in drool, chin, chest and front feet, I could hear him panting in the kitchen from the bedroom, his heart was pounding.
The dog is in a right state because he doesn't want to be separated from you at night.To me,it's a behavioural issue,perhaps some extreme form of separation anxiety.I would certainly work with a trainer,someone who is used to dealing with cavaliers and would be gentle and sensitive.If you're stressed and worried putting him to bed,I feel he would pick up on that and react accordingly.
I don't put our dogs to bed any more because they act up..we have had destroyed dog beds,skirting board eaten etc..my husband now puts them to bed,without any fuss or incident.there's a simple instruction.."Mind the house" ...both get up off the sofa,go to their bed in the laundry room(all baskets removed) and they get a piece of ham or chicken,a fresh bowl of water and that's it for the night.If I put them to bed,the oldest girl is howling like a werewolf and hopping off the door like a cannonball.My fault,not hers...
It's quite easy to blame CM/SM for everything strange and unusual.My Daisy became very withdrawn when in pain,never anything hyperactive like that.She just opted out of life..
It's worth trying the behaviour/training approach before heavily medicating the dog.I would also worry about him injuring himself while in that state.I think you will get to the bottom of it,but not with a neurologist.
Sharing my sofa with Holly, Ivy,Lilly and Hazy.. and never forgetting our beautiful Daisy who reached the bridge too soon.