i have a simular comlaint in my left knee, its at its worst in the winter & when i climb stairs its at its most painfull , it turns out that its arthritious
but the good news is that cycling is good for it as its a low weight bearing exersise. its a case of use it or lose it, my doctor advised so when its sore i just drop down a gear! anti -inflamitaries help ,just disprin does it . i also use a neoprene knee support, mainly to keep it warm in the winter as i wear shorts all year round (only on the bike !) the joys of getting old
keep riding but take it easy .