Child severe pain in left side of abdominal, bruises, night sweats, sore joints, dizziness. Rashes come and go, loss of appetite. Tightness in chest?

Please have your . Child seen by a doctor as soon as possible. Cannot say what is causing his symptoms here-could be many things. But symptoms are very concerning. The doc will ask about his medical history & about symptoms, & do a thorough exam. They will probably want to do some blood tests too. Other tests needed will depend on the exam & findings. Take care.
Best thing to do . Is take your child to the doctor for complete exam and to run some tests. There is a lot of possible causes but need more details and exam which is best handled by your pediatrician.