Sorry this is long.I had pain on and off for years. The odd time it would give way and be a bit painful- didn't happen for another year, and just forgot about it. Over time, it became more frequent. Has yours ever locked or given way? Have you tried anti inflammatory meds like voltarol or ibuprofen?
I eventually did see my GP and was also sent for an MRI. I too had a meniscal tear. I was only 40 at this point and hadn't had any specific injury. The things I tried/had:
-Physio
-I pronate inwards when walking, so a podiatrist recommended certain trainer types to help combat that
-Lost 10kg
The pain continued and I when I had follow up Xrays about 18mths later- I was told the meniscus had gone and I now had osteoarthritis in the knee! I was in agony, not sleeping, could bare walk and couldn't work.
A ortho consultant recommended an offloader knee brace. My arthritis is on the inside side of my knee, and the brace opens up this area and puts your weight down the outside. It was a game changer. I could walk, work and live again without pain! Over time, I had 2 braces. 1 was discrete and more elastic and hide under my trousers. I lost more weight, so this one no longer fitted. I was then given a larger, metal and fitted over clothing. Both were given to my by the hospital physio department. Eventually, I weaned myself off the brace (which the physio recommended I do).
This was 4yrs ago. I've gradually put weight back on, but strangely, the pain has never been as bad as it previously was. Maybe I'd strengthened the mucsles to support it more- I have no idea?
I will need a knee replacement in future, but am holding off till I really need it.
Edited to say- YES, see your GP. I'd had the pain on and off for years before bothering my GP. The 1st thing they said was 'well, you've never been here before about knee pain!'. Well no, I was trying to cope myself! Do go, so its at least on your record and you can get the ball rolling- and hopefully at least an Xray or MRI and physio.