N.S.
You don't say why she must go to an ER versus Urgent Care. If she can, tell her to go to an urgent care center to be seen. Her regular family practioner and maybe her OB probably has an urgent care office associated with their clinic that she can call after hours. They do have limited hours, but they are usually open in early evenings and weekends too. If they find she's really in trouble, they will speed up the waiting process at the hospital and get her admitted faster.
From what you describe, it sounds like she might need antibiotics. If for some reason such as insurance is an issue, try one of those "Minute Clinic" type offices where you can walk in with no appointment. They are open on weekends too. These are in most drug stores, many large grocery chains and even Target stores. They can and will prescribe antibiotics if necessary. There are certain antibiotics that are okay during pregnancy.
Tell her she should not fool around with the possibility of a bacterial type infection prior to delivery. If for some reason she should need an emergency c-section, she'll have a lowered immune system and might have complications with healing etc. Hopefully it's just a bad virus and nothing more. Nonetheless, she needs to get her immune system up and should get a second opinion to be sure nothing more serious is going on.
Good luck!