It sounds exactly like Rheumatoid arthritis. Common symtoms exactly not odd or confusing, just typical. You loosen up after a ride and feel better. A long ride could be worse. Warm up slowly and carefully on every ride. On a long ride you may feel great right at the end and have a lot of inflamation the next day as it slowly gets worse over time. Two days off and you can be ready to ride again and feeling better. Muscles take two days to heal 100% from hard exercise anyway. No loss in riding condition from two days off, maybe even an improvement over the course of the season.
Only a doctor can say for sure. Go to a Rheumatologist. I and millions of others have those exact symptoms, if it is Rheumatoid arthritis, the doctor will probably tell you to keep moving or you will get stiff
DUH !
Go see a doctor now, the current accepted best treatment is agressive treatment early to prevent more damage. You may not have to do anything now, but find a good doctor, to keep on top of it. Eventually you will need one, sooner is much better than later. It can prevent (reduce) damage.

glucosamine+condroitin is for Osteo- not Rheumatiod. It will will say it on the package. Different disease different problems. There's plenty of info on line.

Edit: oops-forgot the good news. I have had it almost all my life, I started missing work from hip pain in the late 70's. Cycling helped a lot. The last few years after a 20 mile warm up, I did at least a century every week. Most of the time more than that.