Usually with viral illness, more than 1 organ system can be involved: eg., With flu-like symptoms, can have loose stools too.
So, as long as you are not giving unusually large doses of multivitamins/
Vitamin.D, unlikely for medicine to cause increased stool frequency: more likely to be a part of the same viral illness.
Next Steps
If high temperature/blood or mucous in stools/tenesmus or painful defecation/persistent symptoms even after 3 days,then might be bacterial gut infection for which doctor should be consulted