Your problem may be the Zoloft. That is a high dose.

SSRIs...over time, increase serotonin activity in the body. Over 90% of the drug works in the body, and only 10% in the brain.
High serotonin levels do all sorts of things. They cause flushing, and tingling in the skin. (some opiates do this too (itching), because they stimulate serotonin release in addition to their pain actions).

http://www.aafp.org/afp/2003/0915/p1135.html
I don't understand Paxil on this list, but cyproheptadine is available in US for use. Pizotifen is not available in US... but I believe it is in Canada. Dr. Jay Cohen, MD who we link to alot here uses it for blocking his erythromelalgia symptoms (in his feet). He mentions on his site getting his from Canada.

Some people who take SSRI drugs for a long time, develop an imbalance of the dopamine. This neurotransmitter may become less available, and when it does, it causes leg cramping and cramping everywhere and muscle twitching. Your concerns about Parkinson's is accurate because that disease is a lowering of dopamine actions too.
This link explains the spasms and other symptoms including itching ..
http://www.drmurphreestore.com/newsl...singtruth.html

I'd discuss with your doctor, tapering off the Zoloft for now. You might be very surprised at how miserable that drug can be.

For now you can try the Morton's Epsom Lotion... Appy to the areas you get the cramping/twitching. It is available at WalMart and Walgreen's locally and also online at Amazon. WalMart's price is amazingly low too.

Do you know you are anemic? I would only use iron if your testing at the doctor's is low. Taking iron when a person is not anemic can lead to heart damage.

I would not raise potassium artificially with supplements. OTC supplements have a maximum allowable amount of 99mg /tablet.
Food sources are safer. Many foods provide good potassium amounts. one V8 juice has 800mg per can. The low sodium has over 1000mg per can!

This link gives potassium content for foods so you can check your diet and see what you are getting. 4500mg is the new daily goal.
This is a sample page for edamame beans. These are precooked and frozen, inexpensive and very good.
http://nutritiondata.self.com/facts/...roducts/9873/2
potassium =676mg
Some frozen veggies now come with them added in a mixture.
I use a Steamer version that has a mix of black beans, edamame, carrots and peas. You can buy them alone...as well, and you just defrost them. Throwing them in boiling water for a minute or two. Then shell them. They make a good snack too. They have a unique butter nutty flavor.
Another good source is pepitas (pumpkin seeds)
Now this serving size on this page is huge...you don't need to
eat that much of course...but see they are good sources of
potassium and magnesium:
http://nutritiondata.self.com/facts/...roducts/3164/2
When you want a snack reach for these rather than pretzels which are empty of anything useful (empty carb calories). We found pepitas at our super Walmart recently...very affordable but made in China which was concerning. Most healthfood places have pumpkin seeds too. I also eat unsalted cashews, which we find at Costco for savings.
This is the page for unsalted cashews:
http://nutritiondata.self.com/facts/...roducts/3094/2
One has to pay attention at NutritionData to the serving sizes they post...some are really huge. But you get the idea anyway.

I think if you get off the SSRI Zoloft, things will improve for you.

main website:
http://nutritiondata.self.com/