Your story reminded me of the long fight my friend Larry had with his gelding "Wart". The poor darling started with some small sarcoids as a two year old---TB and Quarter Horse bloodlines btw. Then suddenly, the sarcoid on the inside of his left knew grew over night and became, not golf ball size, but GRAPEFRUIT size. Larry called the vet immediately and had it surgically removed and cauterized---THAT WAS A HUGE MISTAKE. I have never seen so much blood come from an animal that lived and the sarcoid seemed to get even worse after that.
The internet was new in those days and Larry's whole family are herbalists and between the two sources, we started trying all kinds of alternative therapies---with the blessings of our young vet who was equally baffled by the development of the sarcoids. They were even starting on his face and jaw and we were concerned that they would affect his training in either a bit or a hackmore.
We found a website on the topic of equine sarcoids from the UK and everyone warned us not to cut into or try to remove the sarcoid with surgery or it would cause the abnormal cells to work overtime. That warning came too late as we watched the sarcoid come roaring back with a vengence.
Larry ordered a medication that was really a form of chemotherapy and cost $120 an ounce. I believe it came from a vet in Colorado. It helped, but once the treatment ended, the sarcoids would begin to return.
Then the information on colloidal silver was sent to us and we tried it and a huge change for the better occurred. Due to the expense, Larry even learned to make his own.
I didn't see Wart for a number of years and to my surprise last Spring, instead of discovering that he had been put down-----which was where I was afraid we were headed---I found Wart standing in the pasture without a sarcoid in sight. Larry said that after using the colloidal silver inside and out for the recommended period, there had never been a reoccurence. I was stunned as this horse was as badly affected as any horse I have ever seen.