Ok, I have a strange symptom, and I'm curious if anyone else has this, or has any idea.. No google search is even bringing anything up!

I have been getting IVIG for 3.5 years for my weakness (LEMS high on list), but no definite diagnoses besides "Autoimmune syndrome, and non length dependent SFN). Anyhow I noticed a while back if I use my tongue (like press it against my cheek) for a while, it will feel fatigued and when I look at it, it actually turns purple and splotchy.. All my muscles get that overwhelming fatigue with use (just like my tongue).. so I wonder if they also are doing this.

I have head my heart checked out and it's fine.. My pulse ox is always fine (except when I totally crashed 3.5 years ago). So I don't think its cardiac related.. Any thoughts - does this happen to yall? is that normal for fatigued muscles?