Trouble Finding The Right Magnesium

The best I felt was when I took a liquid magnesium calcium supplement, but I noticed the type of magnesium was magnesium oxide.
I read an article on magensium at this place...
http://george-eby-research.com/html/depression-anxiety.html


And since then have tried...
Magnesium chloride - it always gives me a headache

Magnesium Malate - just one pill - 200mg gives me great stomach upset
Magnesium citrate (200mg)- causes flushing and rapid heartbeat
Here's the funny thing... All of these seem to make my muscle cramps worse, which doesn't make sense to me.
So far it seems magnesium oxide is the only one that when I take it, my muscle cramps and stiffness goes away.
I don't have any more money to buy a bunch more supplements at the moment, but I would like to hear recommendations if anyone has any.
What is best for muscle cramps and stiffness?

Also, I like epsome salt baths once in a while, but I seem really sensitive to that also. If I put too much in the bath at bedtime the next day I get diahrrea. (around a half a cup per large tub full) And sometimes the epsome salt baths cause me to have more muscle cramps also. Why would that be??
I am getting frustrated with trying to get this magnesium stuff figured out.