Vict I once noticed muscel spasm in the left shoulder for serveral minutes, which was in my opinion random and has nothing to do with MK-677 (which I'm taking for the 11th week now, mostly 25mg/ed, went up to 50mg/ed for some days as a test). Use magnesium (watch out for too high doses, otherwise you can get diarrhea) or use taurine, I would say. But according to your post, you are already taking them without any effect. How about your blood sugar? MK-677 can lead to temporary decrease in insuline sensitivity which also may have an impact on these spasm.
I don't know you daily intake on vitamines and minerals but while using a GHS like MK-677 I recommend using higher doses of "everything".
I have honestly no idea in your case. What you can try:
- reduce the dosage (20mg/ed or less, even 10mg/ed had nice effects in studies)
- intake scheme to pre-bed
- ensure to take enough minerals and vitamines, split during the day