I haven't really found anything that stops the Fibro Pain instantly when I am having a flare up but some things do help. (I usually get a flare up if I have done some out of the ordinary heavy lifting, and in between I don't have a lot of pain so I'm lucky that it's not constant). The pain can be so bad at those times that I also become brain foggy and extremely tired. Many of my muscles feel tight and hard like rocks and I can feel arthritic and stiff as well. I find taking marijuana gummies especially Sativa during the day and Indica at night helps. Also taking Epsom Salt Hot Baths helps. Additionally my husband massages all my affected muscles out. I'm very lucky cause he likes doing it. Sometimes he needs to apply so much pressure that I feel bruised afterwards but it's a kind of exquisite pain/pleasure when he massages the muscles out and when he starts I don't want him to stop. I usually have him massage the muscles for many days an hour each time until I feel so bruised yet more flexible and take a break knowing that my body just needs to rest. I have a theory that my body has to clear out the toxins that were created when the muscles became extra stiff and tight. Eating low inflammatory foods and/or low histamine foods seems to help. Changing the diet does seem to help. I avoid Gluten and Dairy and Sugar at these times. Also getting more rest and sleep is important too. Reducing stress is also important. I try and stay positive because I know that eventually the pain dies down and I will feel almost normal again until the next flare up. I try to be careful to do some fibromyalgia exercises on a daily basis to keep the muscles loose and flexible but sometimes I don't exercise as regularly as I would like. Also, drink a lot of water because when you have a flare the muscles need to heal. Hope this helps. You could try taking H1 and H2 blockers like Allegra and Pepcid. These drugs reduce histamines in the body.