I Was Discharged From The Hospital Tuesday Late Afternoon. On

I was discharged from the hospital Tuesday late afternoon. On Thursday I returned back to work n my arm that my iv was in became swollen n felt a bit warm I began using an icepack which helped. That evening also started using heat as well ice was feeling better but today swelling down but still nice size knot planning on going to family doctor Monday or should I return to the ER. How serious is this it from fluid? Thank you