Gosh Starz! You're in a difficult situation in regards to being allergic to antihistamines and steroids. Hopefully, you never experience a severe allergic reaction to anything. Erin brings up a good point. Sometimes it's the fillers that were sensitive or allergic to and not necessarily the medication.

There are natural anti-inflammatories that may help some but I don't think the result will be as big as with steroids. I do know that anthocyanins found in berries (blueberries) and cherries have strong anti-inflammatory properties and can be just as effective as taking an aspirin or ibuprofen. I was researching this for all of my joint issues and some of the studies sound promising.

Some neuros don't use steroids to treat a flare unless it involves the eyes or the flare is severe (been there and spend some time in the hospital with that one). I actually have had more flares that were not treated with steroids than treated with steroids. My neuro does not treat spinal flares with steroids and just offers symptom management.

I think you best option is to discuss this with your neuro and if you do decide to try the IVSM, then request to be admitted to do so given your history. Let us know how you are doing.