ACL reconstruction 6 months post op pain

Hi everyone, I have some questions to ask, and I hope someone will be able to help with this because it's worrying me a lot.

I injured my acl last year and I had a hamstring autograft reconstruction surgery in december. This marks the 6 months recovery period.

In the month of may onwards, I have been doing running, jumps and sprints on a regular basis, and it usually feels fine.

A few days ago, while i was driving, i felt that my knee was a little uncomfortable, so i did a quick full extension to kinda 'crack' it. This having to 'crack' thing happens pretty often me and it makes it feel comfortable and not 'locked'. But this time around when i did it, a sudden jolt of pain came and since then i cant seem to straighten nor stand straight properly without it feeling excruciatingly painful. its swollen too.

I have been putting ice on it for a few days, but the pain is still there. it hurts more after i walk around for awhile. My appointment with my surgeon will be weeks from now. I would like to ask if anyone knows what has happened to me?

Thank you for reading!