Autumn,
80mg to my knowledge is the lowest available dose. Of course one can always take 1/2 a pill but I doubt you'd get much, if any, BP control. All drugs have side effects, including Diovan. It's just that Diovan seems to have very few and at a lower overall incidence. Headache and dizziness are the most commonly reported adverse reactions with it.
However, these effects generally are mild and transient and have only infrequently required discontinuation of therapy.
Hang in there a while. My bet is that your body will adjust and that this is only temporary.
zuzu xx