Mysterious Leg Pain

Saturday morning we noticed that Lucca wasn't putting any weight on his left leg when we would stand him up. This was very odd for him because he LOVES to be up on his feet. He would hold his leg up like a flamingo. When we would try to press on his foot and ankle he would cringe and push our hands away like it was hurting him.. One of the characteristics of Lucca's syndrome is really high pain tolerance, so the fact that he was wincing in pain was a huge indicator that something was wrong. I call my mom and mentioned it to her and she immediately said that she had noticed it the prior day but didn't want to mention it in case it didn't last... so we kept a close eye on it this weekend and it hasn't progressed at all or gotten any better. His left foot is flexed down and inward and when we try to flex his toes up his ankle pops. We took him to the pediatrician today and got xrays from his hip down and nothing it broken. She said there are two other option as to what could be going on... 1. he has something going on with the muscles/tendons, which would require an MRI and they are making us an appt to see the orthopedist sometime this week for him to evaluate Lucca. and 2. he has an infection in his hip called Toxic Synovitis (something like that), which is caused when a child has been fighting a viral infection for quite some time (which he just got over fighting one for like a month!) and the infection settles in the hip joint causing pain and limping, drawing up of the foot, etc. Soooo... very thankful that nothing is broken but hopin we can figure out what is causing his pain and causing him to not want to weightbear AT ALL....