I Am An MS Patient Who Has Been Taking Tecfidera

I am an MS patient who has been taking Tecfidera for approx. 3 years with no real side effects other than occas flushing . Approx 3 weeks ago I was diagnosed with shingles and started on Acyclovir and at that time was told to discontinue my Tedfidera to enable my immune system to fight the shingles and told to resume when the blisters dried up. I started back on the Tecfidera last Saturday am and have had profound nausea and diarrhea since Monday evening. I am wondering a couple things...I know it may be the Tecfidera even tho I haven't had problems prior to this-but I am also worried that perhaps it could be something otherwise compromised by the recent acyclovir (kinda like what can happen with an overgrowth of bacteria when taking antibiotics)