The lumps sound like they could be lymph nodes. If they are swollen your body is fighting inflammation. I get the twitches in my legs a lot. I also get bad restless leg syndrome at night. Magnesium is meant to help but I found I absorb it better through the skin than in my stomach. There probably isn't anything that will fix this for you 100%, but there will be things you can do to improve the cramps and twitching and general soreness. You need a doctor who will listen properly to start with, if you already have a good doc you are half way there... :)

I get bad Muscle twitching I'm on muscle relaxers n they help some. It's not fun

Also, have you tried adding calcium to your diet? Sometimes low calcium can cause sore legs too. If the bumps travel anywhere other than those two places, it might be Dercum's disease.

Have you tried an epsom salt bath versus magnesium supplements? I know that heat can help this pain a lot. RLS is common with FM from what I've seen. Has the doctor checked these lumps? If after the doctor has checked them and says that they're harmless and can give you a name, then maybe see what you can find on the internet. If it is lymph nodes, (an it kinda sounds like it) it is important to find out why.