It's possible your daughter is having an allergic reaction to remicade/infliximab, it is possible it is unrelated. Body wide rashes raise the concern of an allergic/immune reaction to a medication. An allergic reaction can happen when her body has developed remicade-antibodies. You can get a test for remicade-antibodies to confirm or rule that possibility out.
Prometheus Labs in CA originated the blood test to look for antibodies and still offers it for a premium. /www.prometheuslabs.com/Resources/Anser-IFX/Anser_IFX_Product_Detail.pdf
The test is also offered as a generic from a variety of other labs, LabCorps as an example:/www.labcorp.com/test-menu/29496/infliximab-concentration-and-anti-infliximab-antibody
Ask your gasteroenterolgisit and he/she can order this test. It's a simple blood test. Results come back within a couple days. Then you know!