After 2 hard weight workouts this week, my arm is swollen & tight with fluid. This am I had a urinalysis and rhabdo was negative but I am still nervous. Should I go to ER tomorrow if swelling not down?

Depends on who U.... ...R cing. Rabdo. May not b + but protein+ is worrisome. If u r cing a sports med ortho, fellowship trained u r in good hands ; following his/her plan of care, u should b ok. If u just saw ur pcp, may not b familiar with ur problem or with rabdomyolysis.The main symptom of compartment syndrome is severe pain on passive stretching of involved muscles. If+get into an er ; demand ortho consult.
Always call doctor. You have a physician. I would advise calling or paging them before going to the er for a non-life threatening problem, especially one that is already being monitored by your physician.