If it's weird, one of my kids will get it

Do you ever feel like your kids will catch any old sickness going around? Well, my kids often miss the "bugs" going around, but manage to get sick with things no one but the doctor's have heard of. The latest is Samuel. Monday when I dropped him off at school he told me that his leg hurt and I noticed that he was limping a bit. Of course I thought, whatever, he's a 5 year old boy...go to school. However, Tuesday morning he was in tears just walking from his bed to the bedroom door. Trying to streamline things, and figuring that he would need x-rays, I took him to urgent care rather than the pediatrician. We spent a couple hours there and they did x-rays and couldn't find anything other than swelling in his thigh where it hurt, so they wanted to send him to a pediatric orthopedic surgeon. I made the appt for Wed afternoon, but my pediatrician wouldn't give me the referral until I brought Samuel to them. Fine with me, maybe they could figure out what it was and I could skip the specialist. Nope, they didn't know what it was either, but she thought it was the hip, so off for more x-rays. Sure enough, after a nightmare of a parking situation, in which I gave my van to a valet and wasn't sure I would get it back, we were told he has toxic synovitis. Now it sounds horrid, but it really is just a viral infection in the hip (like a cold) and will go away on it's own in a couple of weeks. However, just to make 100% sure it's not bacterial (which would be really bad), Samuel had to go get his blood drawn today. He did very well with this. So...anybody else have kids that get hip colds?