throbbing knee pain after hot shower

Hello . I have servere OA in my knees, the right one being the worst for about 6 years now. This past Saturday morning , I took a hot shower and let it hit my knees with felt good. However , 1 hour later , I started getting painfull , spasmatic pain on my right knee that causes me to jerk my knee and scream in pain . I never had this before. The pain feels like someting inside my knee wants to get out and the throbbing effect feels like something inside the knee that wants to push out. I looked to see if this was visible to the eye but I don't see my skin moving at all. The pain comes back approx every 10-15 minutes . Its Monday and I still get that pain . I took a Flexiril last nite thinking that it might be a muscle spasm but really didn't help. Did that hot shower have a bearing on this new pain ? Does it have anything to do with fluid accumulation in my knee expanding and causing pain due to hot water ? Could something in my knee explode ?

Would appreciate any input. My OA doctor appointment is not until March 19th . Don't know if I can put up with this till then.

Thanks