I'm not a doctor but if this is a more minor illness you can probably treat it yourself, and yea at least starting at a low dosage isn't a bad idea, at least that can be changed and upped if not working but if you start on a higher dosage and get side effects that med effect has to wear off. If it gets worse or lingers I don't think it is wrong to contact a doctor even if the symptoms are not there all the time.

I don't have DID but I can still delay illness if really needed. If I felt ill but some tasks needed to be done, I've been able to put off the illness for a few days. The mind can be quite strong.