I don't know much about
UC in young children but I do know it can be associated with other Autoimmune disorders such as Lupus. Lupus can cause the other symptoms you listed as well as problems with concentration. I am also a mother of young children and do not mean to frighten you at all because the chances are
slim that she may have something like that but I think it would be worth while to discuss with your doctor. When Lupus is caught early it can be much better controlled. Arthritis is also not uncommon to have when you have UC.
HOWEVER - it is more likely that she is just a normal 6 year old - most have short attention spans at that age. My daughter has lots of leg cramps that my doctor thinks are just growing pains. I had those too when I was a child. You might try to make sure she is getting enough potassium which can help joint pains and leg cramps in children. I would also make sure she is getting enough sleep. If she is over-tired she will not concentrate well in school. UC makes us all more prone to fatigue. At her age she still needs 10 - 12 hours of sleep a day. Many parents do not realize that their young school aged kids still need that much sleep. It is hard to get kids to bed early enough if both parents work (as my husband and I do) so I know that is easier said than done but it may be worth a try... As a former teacher, I often had students who seemed hyper-active but in reality they were just not getting enough sleep at night. I hope this helps. I am sure she is totally normal!