What do I do about having really really bad nausea?

Go see another doctor and explain your situation. Sounds like this doctor is giving you meds that give you adverse side effects. Normally when this occurs, they will switch you to other drugs without adverse side effects. Adverse side effects are individualized to a person and so not all drugs work the same way on each person. Also, just curious, but the combination of diagnoses seems rather strange, has he done labs(blood draws) on you to find out what type of infection it is yet? Or is he "winging it" by symptoms?