Knee problems

I'm a 33 yr old female. I'm confused.

I injured my knee a year in march. I have went to doctor after doctor . I have had mri's , x-rays, and cat scans. They only thing they found was my knee bones are rubbing together. I have pain all the time. My knee makes cracking and scrathing noises. I was just told I have D.B.D(Degenerate Bone Disease). My knee gives out all the time. If I sit or stand my knee will lock up . When I stand after sitting for so long my knee will be locked to where I have to actually work my leg to go straight. I have already broken my foot because of my knee going out on me.

I just want to know how they found this? What caused this? They already told me I had arthritis and now this.

If anyone else suffers from this . I just want to know what I'm going to be looking forward too. I just needs some answers and can't seem to get any.
Will someone please help me . I don't even know what D.B.D is. I can't find any info on it .

If anyone has anything that they can tell please do . Thanks :wave: