Can osgood slaughters hurt the back of your knee?

I have had Osgood Slaughters for 3 years now and it still won't go away! Well I have been vacationing in Florida for 2 weeks now so I have been out and about all day everyday which is not healthy for me. But now the back of me knee is hurting really bad? I have been walking in the sand alot and stuff like that. This has been going on for 3 days. I can't walk down the stairs because I lean all my weight on the back of my legs but it doesn't hurt as bad to go up. If I sit down for a while then have to get up it will hurt really bud but after awhile it will stop hurting (or maybe I just don't notice it anymore idk) it doesn't hurt when I swim though. But I don't know what it could be.