Nitrates: artificially added to processed meats (ham, weiners, deli meats), naturally occurring in some fruits & vegetables. Added nitrates are more harmful than naturally occurring ones, which are usually better tolerated.
https://www.livestrong.com/article/541308-fruits-vegetables-that-are-high-in-nitrates/
I did have RLS during pregnancy & years later it reoccurred sporadically. I also heard to eat bananas (not sure about the mag, but they are high in potassium). I never had that work for me.
I did have a bad reoccurrance a few months ago. It made me feel crazy it was so unbearable. I could not keep my legs still. That time, there may have been many factors at play, but it happened after having sat in a tiny car with poor seats for a couple of hours, which I think added to it. It didn't happen on the way there, but did on the way back. I felt like opening the door and jumping out even while it was moving! It was extreme. It took a long time once stopped to get it to calm down & that was only a little. It wasn't until I was at home that I could deal with it further. That is the worst it ever had been.
Possibly if it is magnesium related, an application of magnesium oil (the mag form is magnesium chloride) would get more magnesium into your body without digestive disturbances.
Skinny Moon, did you check the Dr. Axe link? I added it after your reply that followed. The link has a lot of good & varied information.