Good sign that joint pain is less severe on some days? or could it still be lupus? pain always there but some days better than others

Hard to say: Joint pains can have many causes from degenerative osteoarthritis issues to autoimmune things like lupus. But for many pain issues, you will have good and bad days regardless of the cause, so it doesn't necessarily tell you that it is likely one more so than another cause.

See doctor: Joint pain tends to be worse with cold and humid weather. However with your history and at your young age, I recommend that you consult an rheumatologist.