Same experience, and my PCP also says that it's muscle strain.
Oftentimes, muscle issues are from a magnesium/calcium issue. Mainly low magnesium. Magnesium deficiency can also cause the anxiety.
Some of the safer and more effective forms of magnesium include: Taurate, Glycinate and Citrate (latter can be laxitative, so take with food).
i do all the time my doctors told me that it is muscle strain which is assosiaciated with anxiety because we tense up all the time he gave me iboufron,and if your anything like me it hurts more when not using it