If it's wrist RSI, keep your wrists supported whilst sitting or sleeping. I find memory foam pillows good for this.
I know that at the time of applying, heat doesn't feel as tho it is getting near the pain, but if you keep doing it, a wheat heat sack will help you feel better over an evening.
Mine is worse at night. A firm wrist support, either tubi or neoprene can help the sensation that i need to compress my inner forearm to relieve - like a counter pressure.
But honestly, rest from the offending activity and pain relief/ anti inflammatory are the things that will relieve for longest.
I don't have any medical conditions but have a chronic pain syndrome so need ways to manage it so I can function. I find general relaxation techniques or aids help me so baths with muscle soak or lavender oil, rubbing a lavender, clary sage and rosemary oil mix (with almond oil base) into anywhere on my body and cammomile tea (and wine too) really helps. Also if sleep is affected, try sleep hypno. I wouldn't recommend an app unless you know what yoi're doing but if you can afford and have time a relaxation and hynotherapist could save your sanity.
There's not many things as difficult to manage and live with as severe pain so you should throw what you can afford at it now.
Meh to acupuncture but only as its never worked for me
I had a Physio a while back who taped my arms with KT tape - have a look online. It was a huge help to carry on and do stuff but you should do as little as poss while resting initially.
In time, could you quit the activity that's caused it?
My heart goes out to you.
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