Which test to use?

I have to analyze a within-subject experiment with a continuous dependent variable and a categorical dependent variable (brain stimulation: Anode, Cathode, Sham, performed in different sessions separated by 48 hours). Although the order of stimulation (e.g., Sham first, Anode second, Cathode third) is randomized across subjects, I'd like to consider it in my analyses. What kind of analysis should I do? A within-subject ANCOVA with session order as covariate?
I think we need a little bit more information. This sounds like an EEG study. Is this correct? If so, I can give more substantial advice.