Knee Pain

My knee clicks at the back of the knee, feels like a string being strained right in the hinge (these are deffo the technical terms). It doesn't really hurt, just clicks with every revolution. I have had a month off riding to see if it goes away, just wondering if anyone else has had this kind of thing and what they did to get rid of it? Thanks

Well, this went mostly away and very quickly became patellar tendonitis. I haven't ridden a bike for over 3 months now, anyone got any protips? GP was a bit vague. Only got referred to physio today so I imagine it will be a few weeks, so if there are any common exercises I can do to relieve it now, that would be ideal, thanks